Java: Fix linting issues (#4800)

Fix linting issues

java/aiservices/openai/src/main/java/com/microsoft/semantickernel/aiservices/openai/chatcompletion/OpenAIChatCompletion.java

@@ -26,6 +26,7 @@ import com.microsoft.semantickernel.chatcompletion.ChatHistory;
 import com.microsoft.semantickernel.chatcompletion.ChatMessageContent;
 import com.microsoft.semantickernel.chatcompletion.StreamingChatMessageContent;
 import com.microsoft.semantickernel.exceptions.AIException;
+import com.microsoft.semantickernel.exceptions.SKException;
 import com.microsoft.semantickernel.hooks.KernelHooks;
 import com.microsoft.semantickernel.hooks.PreChatCompletionEvent;
 import com.microsoft.semantickernel.orchestration.FunctionResult;
@@ -56,9 +57,15 @@ public class OpenAIChatCompletion implements ChatCompletionService {
     private static final Logger LOGGER = LoggerFactory.getLogger(OpenAIChatCompletion.class);
     private final OpenAIAsyncClient client;
     private final Map<String, ContextVariable<?>> attributes;
+
+    @Nullable
     private final String serviceId;
 
-    public OpenAIChatCompletion(OpenAIAsyncClient client, String modelId, String serviceId) {
+    public OpenAIChatCompletion(
+        OpenAIAsyncClient client,
+        String modelId,
+        @Nullable
+        String serviceId) {
         this.serviceId = serviceId;
         this.client = client;
         this.attributes = new HashMap<>();
@@ -75,6 +82,7 @@ public class OpenAIChatCompletion implements ChatCompletionService {
     }
 
     @Override
+    @Nullable
     public String getServiceId() {
         return serviceId;
     }
@@ -82,8 +90,11 @@ public class OpenAIChatCompletion implements ChatCompletionService {
     @Override
     public Mono<List<ChatMessageContent>> getChatMessageContentsAsync(
         ChatHistory chatHistory,
+        @Nullable
         PromptExecutionSettings promptExecutionSettings,
+        @Nullable
         Kernel kernel,
+        @Nullable
         KernelHooks kernelHooks) {
 
         List<ChatRequestMessage> chatRequestMessages = getChatRequestMessages(chatHistory);
@@ -112,6 +123,7 @@ public class OpenAIChatCompletion implements ChatCompletionService {
     @Override
     public Mono<List<ChatMessageContent>> getChatMessageContentsAsync(
         String prompt,
+        @Nullable
         PromptExecutionSettings promptExecutionSettings,
         Kernel kernel,
         @Nullable
@@ -138,7 +150,9 @@ public class OpenAIChatCompletion implements ChatCompletionService {
 
     private Mono<List<ChatMessageContent>> internalChatMessageContentsAsync(
         List<ChatRequestMessage> chatRequestMessages,
+        @Nullable
         List<FunctionDefinition> functions,
+        @Nullable
         PromptExecutionSettings promptExecutionSettings,
         KernelHooks kernelHooks) {
 
@@ -242,7 +256,8 @@ public class OpenAIChatCompletion implements ChatCompletionService {
      * {"type":"function", "function": {"name":"search-search", "parameters": {"query":"Banksy"}}}
      * where 'name' is <plugin name '-' function name>.
      */
-    private Mono<StreamingChatMessageContent> invokeTool(Kernel kernel, String json) {
+    @SuppressWarnings("UnusedMethod")
+    private Mono<StreamingChatMessageContent<?>> invokeTool(Kernel kernel, String json) {
         try {
             ObjectMapper mapper = new ObjectMapper();
             JsonNode jsonNode = mapper.readTree(json);
@@ -254,8 +269,10 @@ public class OpenAIChatCompletion implements ChatCompletionService {
                 if (result != null) {
                     return result.map(contextVariable -> {
                         String content = contextVariable.getResult();
-                        return new StreamingChatMessageContent(AuthorRole.TOOL, content).setModelId(
-                            id);
+                        if (content == null) {
+                            throw new SKException("Function result must not be null");
+                        }
+                        return new StreamingChatMessageContent<>(AuthorRole.TOOL, content, id);
                     });
                 }
             }
@@ -268,6 +285,7 @@ public class OpenAIChatCompletion implements ChatCompletionService {
     /*
      * The jsonNode should represent: {"name":"search-search", "parameters": {"query":"Banksy"}}}
      */
+    @SuppressWarnings("StringSplitter")
     private Mono<FunctionResult<String>> invokeFunction(Kernel kernel, JsonNode jsonNode) {
         String name = jsonNode.get("name").asText();
         String[] parts = name.split("-");
@@ -298,23 +316,28 @@ public class OpenAIChatCompletion implements ChatCompletionService {
     private static ChatCompletionsOptions getCompletionsOptions(
         ChatCompletionService chatCompletionService,
         List<ChatRequestMessage> chatRequestMessages,
+        @Nullable
         List<FunctionDefinition> functions,
+        @Nullable
         PromptExecutionSettings promptExecutionSettings) {
-            
+
         ChatCompletionsOptions options = new ChatCompletionsOptions(chatRequestMessages)
             .setModel(chatCompletionService.getModelId());
 
         if (promptExecutionSettings == null) {
             return options;
         }
-            
+
         if (promptExecutionSettings.getResultsPerPrompt() < 1
-                || promptExecutionSettings.getResultsPerPrompt() > MAX_RESULTS_PER_PROMPT) {
-            throw new AIException(AIException.ErrorCodes.INVALID_REQUEST, String.format("Results per prompt must be in range between 1 and %d, inclusive.", MAX_RESULTS_PER_PROMPT));
+            || promptExecutionSettings.getResultsPerPrompt() > MAX_RESULTS_PER_PROMPT) {
+            throw new AIException(AIException.ErrorCodes.INVALID_REQUEST,
+                String.format("Results per prompt must be in range between 1 and %d, inclusive.",
+                    MAX_RESULTS_PER_PROMPT));
         }
 
-        List<ChatCompletionsToolDefinition> toolDefinitions = 
-            chatCompletionsToolDefinitions(promptExecutionSettings.getToolCallBehavior(), functions);
+        List<ChatCompletionsToolDefinition> toolDefinitions =
+            chatCompletionsToolDefinitions(promptExecutionSettings.getToolCallBehavior(),
+                functions);
         if (toolDefinitions != null && !toolDefinitions.isEmpty()) {
             options.setTools(toolDefinitions);
             // TODO: options.setToolChoices(toolChoices);
@@ -351,18 +374,22 @@ public class OpenAIChatCompletion implements ChatCompletionService {
         return options;
     }
 
+    @SuppressWarnings("StringSplitter")
     private static List<ChatCompletionsToolDefinition> chatCompletionsToolDefinitions(
+        @Nullable
         ToolCallBehavior toolCallBehavior,
+        @Nullable
         List<FunctionDefinition> functions) {
 
         if (functions == null || functions.isEmpty()) {
             return Collections.emptyList();
         }
-    
-        if (toolCallBehavior == null || !(toolCallBehavior.kernelFunctionsEnabled() || toolCallBehavior.autoInvokeEnabled())) {
+
+        if (toolCallBehavior == null || !(toolCallBehavior.kernelFunctionsEnabled()
+            || toolCallBehavior.autoInvokeEnabled())) {
             return Collections.emptyList();
         }
-        
+
         return functions.stream()
             .filter(function -> {
                 String[] parts = function.getName().split("-");
@@ -384,6 +411,9 @@ public class OpenAIChatCompletion implements ChatCompletionService {
             .map(message -> {
                 AuthorRole authorRole = message.getAuthorRole();
                 String content = message.getContent();
+                if (content == null) {
+                    throw new SKException("ChatMessageContent content must not be null");
+                }
                 return getChatRequestMessage(authorRole, content);
             })
             .collect(Collectors.toList());
@@ -405,7 +435,7 @@ public class OpenAIChatCompletion implements ChatCompletionService {
                 return new ChatRequestToolMessage(content, null);
             default:
                 LOGGER.debug("Unexpected author role: " + authorRole);
-                return null;
+                throw new SKException("Unexpected author role: " + authorRole);
         }
 
     }
@@ -459,7 +489,10 @@ public class OpenAIChatCompletion implements ChatCompletionService {
     private static class ToolContentBuffer implements
         ContentBuffer<ChatCompletionsFunctionToolCall> {
 
+        @Nullable
         private String id = null;
+
+        @Nullable
         private String name = null;
         private List<String> arguments = new ArrayList<>();
 
@@ -575,6 +608,17 @@ public class OpenAIChatCompletion implements ChatCompletionService {
 
         @Override
         public OpenAIChatCompletion build() {
+
+            if (this.client == null) {
+                throw new AIException(AIException.ErrorCodes.INVALID_REQUEST,
+                    "OpenAI client must be provided");
+            }
+
+            if (this.modelId == null || modelId.isEmpty()) {
+                throw new AIException(AIException.ErrorCodes.INVALID_REQUEST,
+                    "OpenAI model id must be provided");
+            }
+
             return new OpenAIChatCompletion(client, modelId, serviceId);
         }
     }

java/aiservices/openai/src/main/java/com/microsoft/semantickernel/aiservices/openai/chatcompletion/ParsedPrompt.java

@@ -2,7 +2,9 @@ package com.microsoft.semantickernel.aiservices.openai.chatcompletion;
 
 import com.azure.ai.openai.models.ChatRequestMessage;
 import com.azure.ai.openai.models.FunctionDefinition;
+import java.util.ArrayList;
 import java.util.List;
+import javax.annotation.Nullable;
 
 class ParsedPrompt {
 
@@ -10,8 +12,12 @@ class ParsedPrompt {
     private final List<FunctionDefinition> functions;
 
     protected ParsedPrompt(List<ChatRequestMessage> parsedMessages,
+        @Nullable
         List<FunctionDefinition> parsedFunctions) {
         this.chatRequestMessages = parsedMessages;
+        if (parsedFunctions == null) {
+            parsedFunctions = new ArrayList<>();
+        }
         this.functions = parsedFunctions;
     }
 

java/aiservices/openai/src/main/java/com/microsoft/semantickernel/aiservices/openai/chatcompletion/XMLPromptParser.java

@@ -144,7 +144,9 @@ class XMLPromptParser {
                         //        },
                         //    },
                         //}
-                        assert functionDefinition != null;
+                        if (functionDefinition == null) {
+                            throw new SKException("Failed to parse function definition");
+                        }
                         if (!parameters.isEmpty()) {
                             StringBuilder sb = new StringBuilder(
                                 "{\"type\": \"object\", \"properties\": {");
@@ -207,11 +209,11 @@ class XMLPromptParser {
         String role,
         String content) {
         try {
-            AuthorRole authorRole = AuthorRole.valueOf(role.toUpperCase());
+            AuthorRole authorRole = AuthorRole.valueOf(role.toUpperCase(Locale.ROOT));
             return OpenAIChatCompletion.getChatRequestMessage(authorRole, content);
         } catch (IllegalArgumentException e) {
             LOGGER.debug("Unknown author role: " + role);
-            return null;
+            throw new SKException("Unknown author role: " + role);
         }
     }
 }

java/aiservices/openai/src/main/java/com/microsoft/semantickernel/aiservices/openai/textcompletion/OpenAITextGenerationService.java

@@ -25,6 +25,7 @@ public class OpenAITextGenerationService implements TextGenerationService {
 
     private final OpenAIAsyncClient client;
     private final Map<String, ContextVariable<?>> attributes;
+    @Nullable
     private final String serviceId;
 
     /// <summary>
@@ -38,7 +39,9 @@ public class OpenAITextGenerationService implements TextGenerationService {
     /// <param name="loggerFactory">The <see cref="ILoggerFactory"/> to use for logging. If null, no logging will be performed.</param>
     public OpenAITextGenerationService(
         OpenAIAsyncClient client,
-        String modelId, String serviceId) {
+        String modelId,
+        @Nullable
+        String serviceId) {
         this.serviceId = serviceId;
         this.client = client;
         attributes = new HashMap<>();
@@ -55,13 +58,16 @@ public class OpenAITextGenerationService implements TextGenerationService {
     }
 
     @Override
+    @Nullable
     public String getServiceId() {
         return serviceId;
     }
 
     @Override
-    public Mono<List<TextContent>> getTextContentsAsync(String prompt,
-        @Nullable PromptExecutionSettings executionSettings, @Nullable Kernel kernel) {
+    public Mono<List<TextContent>> getTextContentsAsync(
+        String prompt,
+        @Nullable PromptExecutionSettings executionSettings,
+        @Nullable Kernel kernel) {
         return this.internalCompleteTextAsync(prompt, executionSettings);
     }
 
@@ -78,6 +84,7 @@ public class OpenAITextGenerationService implements TextGenerationService {
 
     protected Mono<List<TextContent>> internalCompleteTextAsync(
         String text,
+        @Nullable
         PromptExecutionSettings requestSettings) {
 
         CompletionsOptions completionsOptions = getCompletionsOptions(text, requestSettings);
@@ -118,7 +125,9 @@ public class OpenAITextGenerationService implements TextGenerationService {
     }
 
     private CompletionsOptions getCompletionsOptions(
-        String text, PromptExecutionSettings requestSettings) {
+        String text,
+        @Nullable
+        PromptExecutionSettings requestSettings) {
         if (requestSettings == null) {
             return new CompletionsOptions(Collections.singletonList(text))
                 .setMaxTokens(PromptExecutionSettings.DEFAULT_MAX_TOKENS);
@@ -127,8 +136,10 @@ public class OpenAITextGenerationService implements TextGenerationService {
             throw new AIException(AIException.ErrorCodes.INVALID_REQUEST, "Max tokens must be >0");
         }
         if (requestSettings.getResultsPerPrompt() < 1
-                || requestSettings.getResultsPerPrompt() > MAX_RESULTS_PER_PROMPT) {
-            throw new AIException(AIException.ErrorCodes.INVALID_REQUEST, String.format("Results per prompt must be in range between 1 and %d, inclusive.", MAX_RESULTS_PER_PROMPT));
+            || requestSettings.getResultsPerPrompt() > MAX_RESULTS_PER_PROMPT) {
+            throw new AIException(AIException.ErrorCodes.INVALID_REQUEST,
+                String.format("Results per prompt must be in range between 1 and %d, inclusive.",
+                    MAX_RESULTS_PER_PROMPT));
         }
 
         CompletionsOptions options =
@@ -143,12 +154,6 @@ public class OpenAITextGenerationService implements TextGenerationService {
                 .setUser(requestSettings.getUser())
                 .setBestOf(requestSettings.getBestOf())
                 .setLogitBias(new HashMap<>());
-/*
-        if (requestSettings instanceof ChatRequestSettings) {
-            options = options.setStop(requestSettings.getStopSequences());
-        }
-
- */
         return options;
     }
 
@@ -157,7 +162,18 @@ public class OpenAITextGenerationService implements TextGenerationService {
      */
     public static class Builder extends TextGenerationService.Builder {
 
+        @Override
         public TextGenerationService build() {
+
+            if (this.client == null) {
+                throw new AIException(AIException.ErrorCodes.INVALID_REQUEST,
+                    "OpenAI client must be provided");
+            }
+            if (this.modelId == null) {
+                throw new AIException(AIException.ErrorCodes.INVALID_REQUEST,
+                    "OpenAI model id must be provided");
+            }
+
             return new OpenAITextGenerationService(
                 this.client,
                 this.modelId,

java/api-test/integration-tests/src/test/java/com/microsoft/semantickernel/syntaxexamples/Example03_ArgumentsTest.java

@@ -6,7 +6,7 @@ import com.microsoft.semantickernel.orchestration.FunctionResult;
 import com.microsoft.semantickernel.orchestration.contextvariables.KernelArguments;
 import com.microsoft.semantickernel.plugin.KernelPlugin;
 import com.microsoft.semantickernel.plugin.KernelPluginFactory;
-import com.microsoft.semantickernel.samples.syntaxexamples.Example03_Arguments.StaticTextSkill;
+import com.microsoft.semantickernel.samples.syntaxexamples.Example03_Arguments.StaticTextPlugin;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
@@ -22,7 +22,7 @@ public class Example03_ArgumentsTest {
 
         // Load native skill
         KernelPlugin functionCollection =
-            KernelPluginFactory.createFromObject(new StaticTextSkill(), "text");
+            KernelPluginFactory.createFromObject(new StaticTextPlugin(), "text");
 
         KernelArguments arguments = KernelArguments.builder()
             .withInput("Today is: ")

java/api-test/integration-tests/src/test/java/com/microsoft/semantickernel/syntaxexamples/Example05_InlineFunctionDefinitionTest.java

@@ -29,7 +29,7 @@ public class Example05_InlineFunctionDefinitionTest {
             .endpoint("http://localhost:" + wmRuntimeInfo.getHttpPort())
             .buildAsyncClient();
 
-        TextGenerationService textGenerationService = OpenAITextGenerationService.builder()
+        TextGenerationService textGenerationService = TextGenerationService.builder()
             .withOpenAIAsyncClient(client)
             .withModelId("text-davinci-003")
             .build();
@@ -55,6 +55,7 @@ public class Example05_InlineFunctionDefinitionTest {
             """.stripIndent();
 
         var excuseFunction = new KernelFunctionFromPrompt.Builder()
+            .withName("Excuse")
             .withTemplate(promptTemplate)
             .withDefaultExecutionSettings(
                 new PromptExecutionSettings.Builder()

java/samples/pom.xml

@@ -126,6 +126,10 @@
                             <target>${maven.compiler.release}</target>
                             <encoding>${project.build.sourceEncoding}</encoding>
                             <showWarnings>true</showWarnings>
+                            <compilerArgs>
+                                <arg></arg>
+                                <compilerArg></compilerArg>
+                            </compilerArgs>
                         </configuration>
                     </plugin>
 

java/samples/sample-code/pom.xml

@@ -75,6 +75,30 @@
         </dependency>
     </dependencies>
 
+    <profiles>
+        <profile>
+            <id>bug-check</id>
+
+            <activation>
+                <activeByDefault>false</activeByDefault>
+            </activation>
+
+            <build>
+                <plugins>
+                    <!-- Ignore linting on samples -->
+                    <plugin>
+                        <groupId>com.github.spotbugs</groupId>
+                        <artifactId>spotbugs-maven-plugin</artifactId>
+                        <version>${maven.spotbugs-plugin.version}</version>
+                        <configuration>
+                            <skip>true</skip>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
+
     <build>
         <plugins>
             <plugin>

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/plugins/ConversationSummaryPlugin.java

@@ -69,7 +69,8 @@ public class ConversationSummaryPlugin {
     /// <param name="kernel">The <see cref="Kernel"/> containing services, plugins, and other state for use throughout the operation.</param>
     @DefineKernelFunction(
         description = "Given a long conversation transcript, summarize the conversation.",
-        name = "SummarizeConversation"
+        name = "SummarizeConversation",
+        returnType = "java.lang.String"
     )
     public Mono<String> SummarizeConversationAsync(
         @KernelFunctionParameter(
@@ -88,7 +89,8 @@ public class ConversationSummaryPlugin {
     /// <param name="kernel">The <see cref="Kernel"/> containing services, plugins, and other state for use throughout the operation.</param>
     @DefineKernelFunction(
         description = "Given a long conversation transcript, identify action items.",
-        name = "GetConversationActionItems"
+        name = "GetConversationActionItems",
+        returnType = "java.lang.String"
     )
     public Mono<String> GetConversationActionItemsAsync(
         @KernelFunctionParameter(
@@ -107,7 +109,8 @@ public class ConversationSummaryPlugin {
     /// <param name="kernel">The <see cref="Kernel"/> containing services, plugins, and other state for use throughout the operation.</param>
     @DefineKernelFunction(
         description = "Given a long conversation transcript, identify topics worth remembering.",
-        name = "GetConversationTopics"
+        name = "GetConversationTopics",
+        returnType = "java.lang.String"
     )
 
     public Mono<String> GetConversationTopicsAsync(
@@ -127,14 +130,15 @@ public class ConversationSummaryPlugin {
         return Flux.fromIterable(paragraphs)
             .concatMap(paragraph -> {
                 // The first parameter is the input text.
-                return func.invokeAsync(kernel,
-                    new DefaultKernelArguments.Builder()
-                        .withInput(paragraph)
-                        .build(),
-                    ContextVariableTypes.getDefaultVariableTypeForClass(String.class));
+                return func
+                    .invokeAsync(kernel,
+                        new DefaultKernelArguments.Builder()
+                            .withInput(paragraph)
+                            .build(),
+                        ContextVariableTypes.getDefaultVariableTypeForClass(String.class));
             })
             .reduce("", (acc, next) -> {
-                return acc + "\n" + next.getResultVariable();
+                return acc + "\n" + next.getResult();
             });
     }
 }

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example03_Arguments.java

@@ -17,10 +17,12 @@ import reactor.core.publisher.Mono;
  */
 public class Example03_Arguments {
 
-    public static class StaticTextSkill {
+    public static class StaticTextPlugin {
+
         @DefineKernelFunction(
             description = "Change all string chars to uppercase.",
-            name = "Uppercase")
+            name = "Uppercase",
+            returnType = "java.lang.String")
         public static Mono<String> uppercase(
             @KernelFunctionParameter(
                 description = "Text to uppercase",
@@ -29,7 +31,10 @@ public class Example03_Arguments {
             return Mono.just(text.toUpperCase(Locale.ROOT));
         }
 
-        @DefineKernelFunction(description = "Append the day variable", name = "appendDay")
+        @DefineKernelFunction(
+            description = "Append the day variable",
+            name = "appendDay",
+            returnType = "java.lang.String")
         public Mono<String> appendDay(
             @KernelFunctionParameter(description = "Text to append to", name = "input")
             String input,
@@ -43,7 +48,7 @@ public class Example03_Arguments {
 
         // Load native skill
         KernelPlugin functionCollection =
-            KernelPluginFactory.createFromObject(new StaticTextSkill(), "text");
+            KernelPluginFactory.createFromObject(new StaticTextPlugin(), "text");
 
         KernelArguments arguments = KernelArguments.builder()
             .withInput("Today is: ")
@@ -57,6 +62,6 @@ public class Example03_Arguments {
                 String.class)
             .block();
 
-        System.out.println(resultValue.getResultVariable());
+        System.out.println(resultValue.getResult());
     }
 }

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example05_InlineFunctionDefinition.java

@@ -85,7 +85,7 @@ public class Example05_InlineFunctionDefinition {
                     .build(),
                 String.class)
             .block();
-        System.out.println(result.getResultVariable());
+        System.out.println(result.getResult());
 
         result = kernel.invokeAsync(excuseFunction,
                 KernelArguments.builder()
@@ -93,7 +93,7 @@ public class Example05_InlineFunctionDefinition {
                     .build(),
                 String.class)
             .block();
-        System.out.println(result.getResultVariable());
+        System.out.println(result.getResult());
 
         var fixedFunction = KernelFunctionFactory.createFromPrompt(
             "Translate this date " + DateTimeFormatter
@@ -112,7 +112,7 @@ public class Example05_InlineFunctionDefinition {
         FunctionResult<String> fixedFunctionResult = kernel
             .invokeAsync(fixedFunction, null, String.class)
             .block();
-        System.out.println(fixedFunctionResult.getResultVariable());
+        System.out.println(fixedFunctionResult.getResult());
 
     }
 }

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example06_TemplateLanguage.java

@@ -105,6 +105,6 @@ public class Example06_TemplateLanguage {
         // Show the result
         System.out.println("--- Prompt Function result");
         var result = kernel.invokeAsync(kindOfDay, null, String.class).block();
-        System.out.println(result.getResultVariable());
+        System.out.println(result.getResult());
     }
 }

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example09_FunctionTypes.java

@@ -8,6 +8,7 @@ import com.azure.core.credential.AzureKeyCredential;
 import com.azure.core.credential.KeyCredential;
 import com.microsoft.semantickernel.Kernel;
 import com.microsoft.semantickernel.aiservices.openai.textcompletion.OpenAITextGenerationService;
+import com.microsoft.semantickernel.orchestration.FunctionResult;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypeConverter;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypeConverter.NoopConverter;
@@ -18,7 +19,8 @@ import com.microsoft.semantickernel.plugin.annotations.DefineKernelFunction;
 import com.microsoft.semantickernel.plugin.annotations.KernelFunctionParameter;
 import com.microsoft.semantickernel.textcompletion.TextGenerationService;
 import java.nio.file.Path;
-import java.time.LocalDateTime;
+import java.time.Instant;
+import java.time.OffsetDateTime;
 import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatter;
 import java.time.temporal.Temporal;
@@ -115,10 +117,14 @@ public class Example09_FunctionTypes {
             .build();
 
         // Different ways to invoke a function (not limited to these examples)
-        kernel.invokeAsync(plugin.get("NoInputWithVoidResult"), null, String.class).block();
-        kernel.invokeAsync(plugin.get("NoInputTaskWithVoidResult"), null, String.class).block();
+        FunctionResult<?> result = kernel.invokeAsync(plugin.get("NoInputWithVoidResult"), null,
+            String.class).block();
+        System.out.println(result.getResult());
+        result = kernel.invokeAsync(plugin.get("NoInputTaskWithVoidResult"), null, String.class)
+            .block();
+        System.out.println(result.getResult());
 
-        kernel
+        result = kernel
             .invokeAsync(
                 plugin.get("InputDateTimeWithStringResult"),
                 KernelArguments
@@ -132,10 +138,13 @@ public class Example09_FunctionTypes {
                     .build(),
                 String.class
             ).block();
+        System.out.println(result.getResult());
 
-        kernel.invokeAsync(plugin.get("NoInputTaskWithStringResult"), null, String.class).block();
+        result = kernel.invokeAsync(plugin.get("NoInputTaskWithStringResult"), null, String.class)
+            .block();
+        System.out.println(result.getResult());
 
-        kernel.invokeAsync(plugin.get("MultipleInputsWithVoidResult"),
+        result = kernel.invokeAsync(plugin.get("MultipleInputsWithVoidResult"),
                 KernelArguments
                     .builder()
                     .withVariable("x", "x string")
@@ -144,8 +153,9 @@ public class Example09_FunctionTypes {
                     .build(),
                 String.class)
             .block();
+        System.out.println(result.getResult());
 
-        kernel
+        result = kernel
             .invokeAsync(plugin.get("ComplexInputWithStringResult"),
                 KernelArguments
                     .builder()
@@ -164,8 +174,9 @@ public class Example09_FunctionTypes {
                     .build(),
                 String.class)
             .block();
+        System.out.println(result.getResult());
 
-        kernel
+        result = kernel
             .invokeAsync(plugin.get("InputStringTaskWithStringResult"),
                 KernelArguments
                     .builder()
@@ -173,8 +184,9 @@ public class Example09_FunctionTypes {
                     .build(),
                 String.class)
             .block();
+        System.out.println(result.getResult());
 
-        kernel
+        result = kernel
             .invokeAsync(plugin.get("InputStringTaskWithVoidResult"),
                 KernelArguments
                     .builder()
@@ -182,24 +194,80 @@ public class Example09_FunctionTypes {
                     .build(),
                 Void.class)
             .block();
+        System.out.println(result.getResult());
 
-        kernel
+        result = kernel
             .invokeAsync(plugin.get("noInputComplexReturnTypeAsync"),
                 null,
                 Temporal.class)
             .block();
+        System.out.println(result.getResult());
 
-        kernel
+        result = kernel
             .invokeAsync(plugin.get("noInputComplexReturnType"),
                 null,
                 Temporal.class)
             .block();
+        System.out.println(result.getResult());
 
-        kernel
+        // Possibilities for return type combinations:
+        // | Method return type | Declared Function Return Type | Invocation Return type |
+        // |--------------------|-------------------------------|------------------------|
+        // | T                  | T                             | T                      |
+        // | T                  | T                             | V converted from T     |
+
+        // | T                  | U extends T                   | T                      |
+        // | T                  | U extends T                   | U                      |
+        // | T                  | U extends T                   | V converted from U     |
+
+        result = kernel
+            .invokeAsync(plugin.get("conversionScenarioA"),
+                null,
+                OffsetDateTime.class)
+            .block();
+        System.out.println(result.getResult());
+
+        result = kernel
+            .invokeAsync(plugin.get("conversionScenarioA"),
+                null,
+                Instant.class)
+            .block();
+        System.out.println(result.getResult());
+
+        result = kernel
+            .invokeAsync(plugin.get("conversionScenarioB"),
+                null,
+                OffsetDateTime.class)
+            .block();
+        System.out.println(result.getResult());
+
+        result = kernel
+            .invokeAsync(plugin.get("conversionScenarioB"),
+                null,
+                Temporal.class)
+            .block();
+        System.out.println(result.getResult());
+
+        result = kernel
+            .invokeAsync(plugin.get("conversionScenarioB"),
+                null,
+                Instant.class)
+            .block();
+        System.out.println(result.getResult());
+
+        result = kernel
+            .invokeAsync(plugin.get("noInputComplexReturnType"),
+                null,
+                String.class)
+            .block();
+        System.out.println(result.getResult());
+
+        result = kernel
             .invokeAsync(plugin.get("withDefaultValue"),
                 null,
                 String.class)
             .block();
+        System.out.println(result.getResult());
 
         /*
         TODO: support FunctionResult
@@ -254,7 +322,10 @@ public class Example09_FunctionTypes {
         /// <summary>
         /// Example of using a void task function with no input
         /// </summary>
-        @DefineKernelFunction(name = "NoInputTaskWithVoidResult")
+        @DefineKernelFunction(
+            name = "NoInputTaskWithVoidResult",
+            returnType = "java.lang.Void"
+        )
         public Mono<Void> NoInputTaskWithVoidResult() {
             return Mono.fromRunnable(
                 () -> System.out.println("Running this.NoInputTaskWithVoidResult) -> No input"));
@@ -263,7 +334,9 @@ public class Example09_FunctionTypes {
         /// <summary>
         /// Example of using a function with a DateTime input and a string result
         /// </summary>
-        @DefineKernelFunction(name = "InputDateTimeWithStringResult")
+        @DefineKernelFunction(
+            name = "InputDateTimeWithStringResult",
+            returnType = "java.lang.String")
         public String InputDateTimeWithStringResult(
             @KernelFunctionParameter(
                 name = "currentDate",
@@ -281,7 +354,9 @@ public class Example09_FunctionTypes {
         /// <summary>
         /// Example of using a Task function with no input and a string result
         /// </summary>
-        @DefineKernelFunction(name = "NoInputTaskWithStringResult")
+        @DefineKernelFunction(
+            name = "NoInputTaskWithStringResult",
+            returnType = "java.lang.String")
         public Mono<String> NoInputTaskWithStringResult() {
             return Mono.fromCallable(() -> {
                 var result = "string result";
@@ -341,7 +416,10 @@ public class Example09_FunctionTypes {
         /// <summary>
         /// Example using an async task function echoing the input
         /// </summary>
-        @DefineKernelFunction(name = "InputStringTaskWithStringResult")
+        @DefineKernelFunction(
+            name = "InputStringTaskWithStringResult",
+            returnType = "java.lang.String"
+        )
         public Mono<String> InputStringTaskWithStringResult(
 
             @KernelFunctionParameter(
@@ -360,7 +438,10 @@ public class Example09_FunctionTypes {
         /// <summary>
         /// Example using an async void task with string input
         /// </summary>
-        @DefineKernelFunction(name = "InputStringTaskWithVoidResult")
+        @DefineKernelFunction(
+            name = "InputStringTaskWithVoidResult",
+            returnType = "java.lang.Void"
+        )
         public Mono<Void> InputStringTaskWithVoidResult(
             @KernelFunctionParameter(
                 name = "x"
@@ -377,9 +458,9 @@ public class Example09_FunctionTypes {
             name = "noInputComplexReturnTypeAsync",
             returnType = "java.time.temporal.Temporal"
         )
-        public Mono<LocalDateTime> noInputComplexReturnTypeAsync() {
+        public Mono<OffsetDateTime> noInputComplexReturnTypeAsync() {
             return Mono.just(
-                LocalDateTime.now()
+                OffsetDateTime.now()
             );
         }
 
@@ -387,8 +468,8 @@ public class Example09_FunctionTypes {
             name = "noInputComplexReturnType",
             returnType = "java.time.temporal.Temporal"
         )
-        public LocalDateTime noInputComplexReturnType() {
-            return LocalDateTime.now();
+        public OffsetDateTime noInputComplexReturnType() {
+            return OffsetDateTime.now();
         }
 
         @DefineKernelFunction(
@@ -406,6 +487,27 @@ public class Example09_FunctionTypes {
             return Integer.toString(x);
         }
 
+        // Possibilities for return type combinations:
+        // | Method return type | Declared Function Return Type |
+        // |--------------------|-------------------------------|
+        // | T                  | T                             |
+        // | T                  | U extends T                   |
+        @DefineKernelFunction(
+            name = "conversionScenarioA",
+            returnType = "java.time.OffsetDateTime"
+        )
+        public OffsetDateTime conversionScenarioA() {
+            return OffsetDateTime.now();
+        }
+
+        @DefineKernelFunction(
+            name = "conversionScenarioB",
+            returnType = "java.time.temporal.Temporal"
+        )
+        public OffsetDateTime conversionScenarioB() {
+            return OffsetDateTime.now();
+        }
+
         /*
         /// <summary>
         /// Example using a function to return the result of another inner function

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example13_ConversationSummaryPlugin.java

@@ -170,7 +170,7 @@ public class Example13_ConversationSummaryPlugin {
             );
 
         System.out.println("Generated Action Items:");
-        System.out.println(summary.block().getResultVariable());
+        System.out.println(summary.block().getResult());
     }
 
     private static void getConversationTopicsAsync() {
@@ -191,7 +191,7 @@ public class Example13_ConversationSummaryPlugin {
             );
 
         System.out.println("Generated Topics:");
-        System.out.println(summary.block().getResultVariable());
+        System.out.println(summary.block().getResult());
     }
 
 
@@ -203,7 +203,7 @@ public class Example13_ConversationSummaryPlugin {
         KernelPlugin conversationSummaryPlugin = KernelPluginFactory.createFromObject(
             new ConversationSummaryPlugin(), null);
 
-        Mono<FunctionResult<String>> summary = kernel
+        FunctionResult<String> summary = kernel
             .invokeAsync(
                 conversationSummaryPlugin
                     .getFunctions()
@@ -212,10 +212,10 @@ public class Example13_ConversationSummaryPlugin {
                     .withInput(ChatTranscript)
                     .build(),
                 String.class
-            );
+            ).block();
 
         System.out.println("Generated Summary (This may take some time):");
-        System.out.println(summary.block().getResultVariable());
+        System.out.println(summary.getResult());
     }
 
     private static Kernel initializeKernel() {

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example27_PromptFunctionsUsingChatGPT.java

@@ -58,7 +58,7 @@ public class Example27_PromptFunctionsUsingChatGPT {
                 ContextVariableTypes.getDefaultVariableTypeForClass(String.class)
             )
             .block();
-        System.out.println(result.getResultVariable());
+        System.out.println(result.getResult());
 
     }
 }

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example56_TemplateMethodFunctionsWithMultipleArguments.java

@@ -85,7 +85,7 @@ public class Example56_TemplateMethodFunctionsWithMultipleArguments {
         // Show the result
         System.out.println("--- Prompt Function result");
         var result = kernel.invokeAsync(haiku, arguments, String.class).block();
-        System.out.println(result.getResultVariable());
+        System.out.println(result.getResult());
     }
 
 }

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example58_ConfigureExecutionSettings.java

@@ -65,7 +65,7 @@ public class Example58_ConfigureExecutionSettings {
             String.class
         ).block();
 
-        System.out.println(result.getResultVariable());
+        System.out.println(result.getResult());
 
         // Option 2:
         // Load prompt template configuration including the execution settings from a JSON payload
@@ -92,6 +92,6 @@ public class Example58_ConfigureExecutionSettings {
         var func = KernelFunctionFactory.createFromPrompt(promptConfig, null);
 
         result = kernel.invokeAsync(func, null, String.class).block();
-        System.out.println(result.getResultVariable());
+        System.out.println(result.getResult());
     }
 }

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example61_MultipleLLMs.java

@@ -85,7 +85,7 @@ public class Example61_MultipleLLMs {
             .build();
 
         var result = kernel.invokeAsync(func, arguments, String.class).block();
-        System.out.println(result.getResultVariable());
+        System.out.println(result.getResult());
     }
 
 
@@ -108,7 +108,7 @@ public class Example61_MultipleLLMs {
             String.class
         ).block();
 
-        System.out.println(result.getResultVariable());
+        System.out.println(result.getResult());
     }
 
 
@@ -141,7 +141,7 @@ public class Example61_MultipleLLMs {
                 String.class)
             .block();
 
-        System.out.println(result.getResultVariable());
+        System.out.println(result.getResult());
     }
 
 }

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example62_CustomAIServiceSelector.java

@@ -78,7 +78,7 @@ public class Example62_CustomAIServiceSelector {
             .build();
 
         var result = kernel.invokeAsync(func, arguments, String.class).block();
-        System.out.println(result.getResultVariable());
+        System.out.println(result.getResult());
     }
 
     // A dumb AIServiceSelector that just returns the first service and execution settings it finds

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example63_ChatCompletionPrompts.java

@@ -55,14 +55,14 @@ public class Example63_ChatCompletionPrompts {
         System.out.println("Chat Prompt:");
         System.out.println(chatPrompt);
         System.out.println("Chat Prompt Result:");
-        System.out.println(chatPromptResult.getResultVariable());
+        System.out.println(chatPromptResult.getResult());
 
         CountDownLatch cdl = new CountDownLatch(1);
         System.out.println("Chat Prompt Result:");
         kernel
             .invokeAsync(chatSemanticFunction, null, String.class)
             .doFinally(x -> cdl.countDown())
-            .subscribe(result -> System.out.println(result.getResultVariable()));
+            .subscribe(result -> System.out.println(result.getResult()));
 
         cdl.await();
     }

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example64_MultiplePromptTemplates.java

@@ -82,6 +82,6 @@ public class Example64_MultiplePromptTemplates {
             .build();
 
         var result = kernel.invokeAsync(function, arguments, String.class).block();
-        System.out.println(result.getResultVariable());
+        System.out.println(result.getResult());
     }
 }

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/Example69_MutableKernelPlugin.java

@@ -25,8 +25,8 @@ public class Example69_MutableKernelPlugin {
         System.out.println("======== Example69_MutableKernelPlugin ========");
 
         KernelPlugin plugin = new KernelPlugin("Plugin", "Mutable plugin", null);
-        plugin.getFunctions().put("dateFunction", KernelFunctionFactory.createFromMethod(
-            Time.class.getMethod("date"), new Time(), "date", null, null, null));
+        plugin.addFunction(KernelFunctionFactory.createFromMethod(
+            Time.class.getMethod("date"), new Time(), "dateFunction", null, null, null));
 
         Kernel kernel = Kernel.builder().build();
         kernel.getPlugins().add(plugin);

java/samples/sample-code/src/main/java/com/microsoft/semantickernel/samples/syntaxexamples/RunAll.java

@@ -0,0 +1,67 @@
+package com.microsoft.semantickernel.samples.syntaxexamples;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Scanner;
+
+/**
+ * Run all the syntax examples.
+ * <p>
+ * Refer to the <a href=
+ * "https://github.com/microsoft/semantic-kernel/blob/experimental-java/java/samples/sample-code/README.md">
+ * README</a> for configuring your environment to run the examples.
+ */
+public class RunAll {
+
+    public interface MainMethod {
+
+        void run(String[] args) throws Exception;
+    }
+
+    public static void main(String[] args) {
+        List<MainMethod> mains = Arrays.asList(
+            Example01_NativeFunctions::main,
+            Example03_Arguments::main,
+            Example05_InlineFunctionDefinition::main,
+            Example06_TemplateLanguage::main,
+            Example08_RetryHandler::main,
+            Example09_FunctionTypes::main,
+            Example10_DescribeAllPluginsAndFunctions::main,
+            //Example11_WebSearchQueries::main,
+            Example13_ConversationSummaryPlugin::main,
+            Example17_ChatGPT::main,
+            //Example26_AADAuth::main,
+
+            Example27_PromptFunctionsUsingChatGPT::main,
+            Example30_ChatWithPrompts::main,
+            Example33_Chat::main,
+            Example41_HttpClientUsage::main,
+            Example43_GetModelResult::main,
+            Example44_MultiChatCompletion::main,
+            Example49_LogitBias::main,
+            Example55_TextChunker::main,
+            Example56_TemplateMethodFunctionsWithMultipleArguments::main,
+            Example57_KernelHooks::main,
+            Example58_ConfigureExecutionSettings::main,
+            Example61_MultipleLLMs::main,
+            Example62_CustomAIServiceSelector::main,
+            Example63_ChatCompletionPrompts::main,
+            Example64_MultiplePromptTemplates::main,
+            Example69_MutableKernelPlugin::main
+        );
+
+        Scanner scanner = new Scanner(System.in);
+        mains.forEach(mainMethod -> {
+            try {
+
+                System.out.println("========================================");
+                mainMethod.run(args);
+
+                System.out.println("Press any key to continue...");
+                scanner.nextLine();
+            } catch (Exception e) {
+                throw new RuntimeException(e);
+            }
+        });
+    }
+}

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/AIService.java

@@ -2,62 +2,75 @@
 package com.microsoft.semantickernel;
 
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
-import javax.annotation.Nullable;
 import java.util.Map;
+import javax.annotation.Nullable;
 
 /**
- * Marker interface for AI services 
+ * Marker interface for AI services
  */
 public interface AIService {
 
     Map<String, ContextVariable<?>> getAttributes();
-    
+
     /**
      * Key used to store the model identifier in the {@code attributes} map.
-     */ 
-    static final String MODEL_ID_KEY = "ModelId";
+     */
+    String MODEL_ID_KEY = "ModelId";
 
     /**
      * Key used to store the endpoint in the {@code attributes} map.
-     */ 
-    static final String ENDPOINT_KEY = "Endpoint";
+     */
+    String ENDPOINT_KEY = "Endpoint";
 
     /**
      * Key used to store the API version in the {@code attributes} map.
-     */ 
-
-    static final String API_VERSION_KEY = "ApiVersion";
-
-    /** 
-     * Gets the model identifier from the {@code attributes} map.
-     * @return The model identifier if it was specified in the service's attributes; otherwise, null.
      */
-    default String getModelId() { return getAttribute(this, MODEL_ID_KEY); }
+
+    String API_VERSION_KEY = "ApiVersion";
+
+    /**
+     * Gets the model identifier from the {@code attributes} map.
+     *
+     * @return The model identifier if it was specified in the service's attributes; otherwise,
+     * null.
+     */
+    @Nullable
+    default String getModelId() {
+        return getAttribute(this, MODEL_ID_KEY);
+    }
 
     /**
      * Gets the endpoint from the {@code attributes} map.
+     *
      * @return The endpoint if it was specified in the service's attributes; otherwise, null.
      */
-    default String getEndpoint() { return getAttribute(this, ENDPOINT_KEY); }
+    @Nullable
+    default String getEndpoint() {
+        return getAttribute(this, ENDPOINT_KEY);
+    }
 
     /**
      * Gets the API version from the {@code attributes} map.
+     *
      * @return The API version if it was specified in the service's attributes; otherwise, null.
      */
-    default String getApiVersion() { return getAttribute(this, API_VERSION_KEY); }
+    @Nullable
+    default String getApiVersion() {
+        return getAttribute(this, API_VERSION_KEY);
+    }
 
+    @Nullable
     String getServiceId();
 
     /// <summary>
     /// Gets the specified attribute.
     /// </summary>
     @Nullable
-    static String getAttribute(AIService service, String key)
-    {
+    static String getAttribute(AIService service, String key) {
         if (service.getAttributes() != null) {
             ContextVariable<?> contextVariable = service.getAttributes().get(key);
             if (contextVariable != null) {
-                return contextVariable.getValue().toString();
+                return contextVariable.getValue(String.class);
             }
         }
         return null;

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/Kernel.java

@@ -5,11 +5,14 @@ import com.microsoft.semantickernel.builders.Buildable;
 import com.microsoft.semantickernel.builders.SemanticKernelBuilder;
 import com.microsoft.semantickernel.hooks.KernelHooks;
 import com.microsoft.semantickernel.orchestration.FunctionResult;
+import com.microsoft.semantickernel.orchestration.FunctionResultMetadata;
 import com.microsoft.semantickernel.orchestration.KernelFunction;
+import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableType;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypeConverter.NoopConverter;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypes;
 import com.microsoft.semantickernel.orchestration.contextvariables.KernelArguments;
+import com.microsoft.semantickernel.orchestration.contextvariables.NullContextVariable;
 import com.microsoft.semantickernel.plugin.KernelPlugin;
 import com.microsoft.semantickernel.plugin.KernelPluginCollection;
 import com.microsoft.semantickernel.semanticfunctions.PromptTemplate;
@@ -98,20 +101,41 @@ public class Kernel implements Buildable {
 
         kernelHooks = mergeInGlobalHooks(kernelHooks);
 
-        ContextVariableType<T> contextVariable;
+        ContextVariableType<?> contextVariable = getContextVariableType(function, resultType);
+
+        return function
+            .invokeAsync(this, arguments, kernelHooks, contextVariable)
+            .map(it -> {
+                return new FunctionResult<>(
+                    ContextVariable.convert(it.getResult(), resultType),
+                    it.getMetadata()
+                );
+            })
+            .defaultIfEmpty(
+                new FunctionResult<>(
+                    new NullContextVariable<>(resultType),
+                    new FunctionResultMetadata()));
+    }
+
+    @Nullable
+    private static <T> ContextVariableType<?> getContextVariableType(
+        KernelFunction function,
+        Class<T> resultType) {
+
+        Class functionReturnType = function.getMetadata().getReturnParameter().getParameterType();
 
         try {
-            contextVariable = ContextVariableTypes.getDefaultVariableTypeForClass(resultType);
+            return ContextVariableTypes.getDefaultVariableTypeForClass(
+                functionReturnType);
         } catch (Exception e) {
-            if (resultType.isAssignableFrom(
-                function.getMetadata().getReturnParameter().getParameterType())) {
-                contextVariable = new ContextVariableType<>(new NoopConverter<>(resultType),
-                    resultType);
+            if (functionReturnType.isAssignableFrom(resultType)) {
+                return new ContextVariableType<>(
+                    new NoopConverter<>(functionReturnType),
+                    functionReturnType);
             } else {
-                throw e;
+                return null;
             }
         }
-        return function.invokeAsync(this, arguments, kernelHooks, contextVariable);
     }
 
     public <T> Mono<FunctionResult<T>> invokeAsync(

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/KernelContent.java

@@ -1,9 +1,6 @@
 package com.microsoft.semantickernel;
 
 import com.microsoft.semantickernel.orchestration.FunctionResultMetadata;
-import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
-import java.util.Map;
-import javax.annotation.CheckForNull;
 import javax.annotation.Nullable;
 
 public abstract class KernelContent<T extends KernelContent<T>> {
@@ -11,7 +8,7 @@ public abstract class KernelContent<T extends KernelContent<T>> {
     @Nullable
     private Object innerContent;
     @Nullable
-    private String modelId;
+    private final String modelId;
     @Nullable
     private FunctionResultMetadata metadata;
 
@@ -30,25 +27,26 @@ public abstract class KernelContent<T extends KernelContent<T>> {
         }
     }
 
-    T setInnerContent(@Nullable Object innerContent) {
+    KernelContent<T> setInnerContent(@Nullable Object innerContent) {
         this.innerContent = innerContent;
-        return (T) this;
+        return this;
     }
 
-    @CheckForNull
+    @Nullable
     public Object getInnerContent() {
         return innerContent;
     }
 
-    @CheckForNull
+    @Nullable
     public String getModelId() {
         return modelId;
     }
 
-    @CheckForNull
+    @Nullable
     public FunctionResultMetadata getMetadata() {
         return metadata;
     }
 
+    @Nullable
     public abstract String getContent();
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/StreamingKernelContent.java

@@ -24,7 +24,7 @@ public abstract class StreamingKernelContent<T> {
     /// The model ID used to generate the content.
     /// </summary>
     @Nullable
-    private final String modelId;
+    private String modelId;
 
     /// <summary>
     /// The metadata associated with the content.
@@ -32,18 +32,14 @@ public abstract class StreamingKernelContent<T> {
     @Nullable
     private final Map<String, ContextVariable<?>> metadata;
 
-    protected StreamingKernelContent(@Nullable T innerContent, int choiceIndex,
-        @Nullable String modelId, @Nullable Map<String, ContextVariable<?>> metadata) {
+    protected StreamingKernelContent(
+        @Nullable T innerContent,
+        int choiceIndex,
+        @Nullable String modelId,
+        @Nullable Map<String, ContextVariable<?>> metadata) {
         this.innerContent = innerContent;
         this.choiceIndex = choiceIndex;
         this.modelId = modelId;
         this.metadata = metadata;
     }
-
-
-    public abstract byte[] toByteArray();
-
-    public Object getInnerContent() {
-        return innerContent;
-    }
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/chatcompletion/AuthorRole.java

@@ -16,18 +16,9 @@ public enum AuthorRole {
         return role;
     }
 
-    public AuthorRole fromString(String role) {
-        for (AuthorRole authorRole : AuthorRole.values()) {
-            if (authorRole.role.equalsIgnoreCase(role)) {
-                return authorRole;
-            }
-        }
-        return null;
-    }
-
     private final String role;
 
-    private AuthorRole(String role) {
+    AuthorRole(String role) {
         this.role = role;
     }
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/chatcompletion/ChatCompletionService.java

@@ -11,6 +11,7 @@ import com.microsoft.semantickernel.builders.ServiceLoadUtil;
 import com.microsoft.semantickernel.hooks.KernelHooks;
 import com.microsoft.semantickernel.orchestration.PromptExecutionSettings;
 import java.util.List;
+import javax.annotation.Nullable;
 import reactor.core.publisher.Mono;
 
 public interface ChatCompletionService extends Buildable, TextAIService {
@@ -36,8 +37,10 @@ public interface ChatCompletionService extends Buildable, TextAIService {
 
     Mono<List<ChatMessageContent>> getChatMessageContentsAsync(
         String prompt,
+        @Nullable
         PromptExecutionSettings promptExecutionSettings,
         Kernel kernel,
+        @Nullable
         KernelHooks kernelHooks
     );
 
@@ -49,8 +52,13 @@ public interface ChatCompletionService extends Buildable, TextAIService {
 
     abstract class Builder implements SemanticKernelBuilder<ChatCompletionService> {
 
+        @Nullable
         protected OpenAIAsyncClient client;
+
+        @Nullable
         protected String modelId;
+
+        @Nullable
         protected String serviceId;
 
 

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/chatcompletion/ChatMessageContent.java

@@ -13,6 +13,7 @@ import javax.annotation.Nullable;
 public class ChatMessageContent extends KernelContent<ChatMessageContent> {
 
     private AuthorRole authorRole;
+    @Nullable
     private String content;
     @Nullable
     private List<KernelContent> items;
@@ -52,13 +53,14 @@ public class ChatMessageContent extends KernelContent<ChatMessageContent> {
 
     public ChatMessageContent(
         AuthorRole authorRole,
-        List<KernelContent> items,
+        List<KernelContent<?>> items,
         String modelId,
         String innerContent,
         Charset encoding,
         FunctionResultMetadata metadata
     ) {
         super(innerContent, modelId, metadata);
+        this.content = null;
         this.authorRole = authorRole;
         this.encoding = encoding != null ? encoding : StandardCharsets.UTF_8;
         this.items = new ArrayList<>(items);
@@ -72,11 +74,13 @@ public class ChatMessageContent extends KernelContent<ChatMessageContent> {
         this.authorRole = authorRole;
     }
 
+    @Nullable
+    @Override
     public String getContent() {
         return content;
     }
 
-    public void setContent(String content) {
+    public void setContent(@Nullable String content) {
         this.content = content;
     }
 

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/chatcompletion/StreamingChatMessageContent.java

@@ -1,33 +1,38 @@
 // Copyright (c) Microsoft. All rights reserved.
 package com.microsoft.semantickernel.chatcompletion;
 
+import com.microsoft.semantickernel.StreamingKernelContent;
+import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.util.Map;
+import javax.annotation.Nullable;
 
-import com.microsoft.semantickernel.StreamingKernelContent;
-import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
-
-public class StreamingChatMessageContent extends StreamingKernelContent {
+public class StreamingChatMessageContent<T> extends StreamingKernelContent<T> {
 
     private final String content;
     private final AuthorRole role;
     private Charset encoding;
-    private String modelId;
 
     public StreamingChatMessageContent(
         AuthorRole role,
-        String content) {
-        this(role, content, null, 0, null, null, null);
+        String content,
+        @Nullable
+        String modelId) {
+        this(role, content, null, 0, modelId, null, null);
     }
 
     public StreamingChatMessageContent(
         AuthorRole role,
         String content,
-        Object innerContent,
+        @Nullable
+        T innerContent,
         int choiceIndex,
+        @Nullable
         String modelId,
+        @Nullable
         Charset encoding,
+        @Nullable
         Map<String, ContextVariable<?>> metadata) {
         super(innerContent, choiceIndex, modelId, metadata);
         this.role = role;
@@ -40,11 +45,6 @@ public class StreamingChatMessageContent extends StreamingKernelContent {
         return content != null ? content : "";
     }
 
-    @Override
-    public byte[] toByteArray() {
-        return toString().getBytes(encoding);
-    }
-
     public String getContent() {
         return content;
     }
@@ -57,18 +57,9 @@ public class StreamingChatMessageContent extends StreamingKernelContent {
         return encoding;
     }
 
-    public StreamingChatMessageContent setEncoding(Charset encoding) {
+    public StreamingChatMessageContent<T> setEncoding(Charset encoding) {
         this.encoding = encoding;
         return this;
     }
-
-    public StreamingChatMessageContent setModelId(String modelId) {
-        this.modelId = modelId;
-        return this;
-    }
-
-    public String getModelId() {
-        return modelId;
-    }
 }
 

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/exceptions/SkillsNotFoundException.java

@@ -1,42 +0,0 @@
-// Copyright (c) Microsoft. All rights reserved.
-package com.microsoft.semantickernel.exceptions;
-
-import javax.annotation.Nonnull;
-import javax.annotation.Nullable;
-
-public class SkillsNotFoundException extends SKException {
-
-    private final ErrorCodes errorCode;
-
-    public SkillsNotFoundException(@Nonnull ErrorCodes errorCodes) {
-        this(errorCodes, null, null);
-    }
-
-    public SkillsNotFoundException(@Nonnull ErrorCodes errorCodes, @Nullable String message) {
-        this(errorCodes, message, null);
-    }
-
-    public SkillsNotFoundException(
-            @Nonnull ErrorCodes errorCodes, @Nullable String message, @Nullable Throwable cause) {
-        super(formatDefaultMessage(errorCodes.getMessage(), message), cause);
-        this.errorCode = errorCodes;
-    }
-
-    public ErrorCodes getErrorCode() {
-        return errorCode;
-    }
-
-    public enum ErrorCodes {
-        SKILLS_NOT_FOUND("Skills not found");
-
-        final String message;
-
-        ErrorCodes(String message) {
-            this.message = message;
-        }
-
-        String getMessage() {
-            return message;
-        }
-    }
-}

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/hooks/FunctionInvokedEvent.java

@@ -3,14 +3,18 @@ package com.microsoft.semantickernel.hooks;
 import com.microsoft.semantickernel.orchestration.FunctionResult;
 import com.microsoft.semantickernel.orchestration.KernelFunction;
 import com.microsoft.semantickernel.orchestration.contextvariables.KernelArguments;
+import javax.annotation.Nullable;
 
 public class FunctionInvokedEvent<T> implements KernelHookEvent {
 
     private final KernelFunction function;
+    @Nullable
     private final KernelArguments arguments;
     private final FunctionResult<T> result;
 
-    public FunctionInvokedEvent(KernelFunction function, KernelArguments arguments,
+    public FunctionInvokedEvent(
+        KernelFunction function,
+        @Nullable KernelArguments arguments,
         FunctionResult<T> result) {
         this.function = function;
         this.arguments = arguments;
@@ -21,6 +25,7 @@ public class FunctionInvokedEvent<T> implements KernelHookEvent {
         return function;
     }
 
+    @Nullable
     public KernelArguments getArguments() {
         return arguments;
     }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/hooks/FunctionInvokingEvent.java

@@ -2,13 +2,15 @@ package com.microsoft.semantickernel.hooks;
 
 import com.microsoft.semantickernel.orchestration.KernelFunction;
 import com.microsoft.semantickernel.orchestration.contextvariables.KernelArguments;
+import javax.annotation.Nullable;
 
 public class FunctionInvokingEvent implements KernelHookEvent {
 
     private final KernelFunction function;
+    @Nullable
     private final KernelArguments arguments;
 
-    public FunctionInvokingEvent(KernelFunction function, KernelArguments arguments) {
+    public FunctionInvokingEvent(KernelFunction function, @Nullable KernelArguments arguments) {
         this.function = function;
         this.arguments = arguments;
     }
@@ -17,6 +19,7 @@ public class FunctionInvokingEvent implements KernelHookEvent {
         return function;
     }
 
+    @Nullable
     public KernelArguments getArguments() {
         return arguments;
     }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/DefaultKernelFunction.java

@@ -1,5 +1,6 @@
 package com.microsoft.semantickernel.orchestration;
 
+import com.microsoft.semantickernel.Todo;
 import java.util.Collections;
 import java.util.Map;
 import javax.annotation.Nullable;
@@ -43,23 +44,19 @@ public abstract class DefaultKernelFunction implements KernelFunction {
     }
 
     @Override
-    public String toFullyQualifiedName() {
-        return null;
-    }
-
-    @Override
+    @Nullable
     public String getDescription() {
-        return null;
+        return metadata.getDescription();
     }
 
     @Override
     public String toEmbeddingString() {
-        return null;
+        throw new Todo();
     }
 
     @Override
     public String toManualString(boolean includeOutputs) {
-        return null;
+        throw new Todo();
     }
 
     @Override

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/FunctionResult.java

@@ -1,22 +1,25 @@
 package com.microsoft.semantickernel.orchestration;
 
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
+import javax.annotation.Nullable;
 
 public class FunctionResult<T> {
 
     private final ContextVariable<T> result;
     private final FunctionResultMetadata metadata;
 
-    public FunctionResult(ContextVariable<T> result, FunctionResultMetadata metadata) {
+    public FunctionResult(
+        ContextVariable<T> result,
+        @Nullable FunctionResultMetadata metadata) {
         this.result = result;
-        this.metadata = metadata;
+        this.metadata = metadata == null ? FunctionResultMetadata.empty() : metadata;
     }
 
     public FunctionResult(ContextVariable<T> of) {
         this(of, FunctionResultMetadata.empty());
     }
 
-
+    @Nullable
     public T getResult() {
         return result.getValue();
     }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/FunctionResultMetadata.java

@@ -4,6 +4,7 @@ import com.azure.ai.openai.models.CompletionsUsage;
 import com.microsoft.semantickernel.orchestration.contextvariables.CaseInsensitiveMap;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
 import java.time.OffsetDateTime;
+import javax.annotation.Nullable;
 
 public class FunctionResultMetadata {
 
@@ -14,6 +15,10 @@ public class FunctionResultMetadata {
 
     private final CaseInsensitiveMap<ContextVariable<?>> metadata;
 
+    public FunctionResultMetadata() {
+        this.metadata = new CaseInsensitiveMap<>();
+    }
+
     public FunctionResultMetadata(CaseInsensitiveMap<ContextVariable<?>> metadata) {
         this.metadata = new CaseInsensitiveMap<>(metadata);
     }
@@ -39,15 +44,30 @@ public class FunctionResultMetadata {
         return new CaseInsensitiveMap<>(metadata);
     }
 
+    @Nullable
     public String getId() {
-        return metadata.get(ID).getValue(String.class);
+        ContextVariable<?> id = metadata.get(ID);
+        if (id == null) {
+            return null;
+        }
+        return id.getValue(String.class);
     }
 
+    @Nullable
     public CompletionsUsage getUsage() {
-        return metadata.get(USAGE).getValue(CompletionsUsage.class);
+        ContextVariable<?> usage = metadata.get(USAGE);
+        if (usage == null) {
+            return null;
+        }
+        return usage.getValue(CompletionsUsage.class);
     }
 
+    @Nullable
     public OffsetDateTime getCreatedAt() {
-        return metadata.get(CREATED_AT).getValue(OffsetDateTime.class);
+        ContextVariable<?> createdAt = metadata.get(CREATED_AT);
+        if (createdAt == null) {
+            return null;
+        }
+        return createdAt.getValue(OffsetDateTime.class);
     }
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/KernelFunction.java

@@ -33,16 +33,11 @@ public interface KernelFunction extends Buildable {
      */
     String getName();
 
-    /**
-     * The function to create a fully qualified name for
-     *
-     * @return A fully qualified name for a function
-     */
-    String toFullyQualifiedName();
-
     /**
      * @return A description of the function
      */
+
+    @Nullable
     String getDescription();
 
     /**
@@ -80,41 +75,46 @@ public interface KernelFunction extends Buildable {
     <T> Mono<FunctionResult<T>> invokeAsync(
         Kernel kernel,
         @Nullable KernelArguments arguments,
-        ContextVariableType<T> variableType);
+        @Nullable ContextVariableType<T> variableType);
 
     <T> Mono<FunctionResult<T>> invokeAsync(
         Kernel kernel,
         @Nullable KernelArguments arguments,
         KernelHooks kernelHooks,
-        ContextVariableType<T> variableType);
+        @Nullable ContextVariableType<T> variableType);
 
     @Nullable
     Map<String, PromptExecutionSettings> getExecutionSettings();
 
     interface FromPromptBuilder {
 
-        FromPromptBuilder withName(String name);
+        FromPromptBuilder withName(@Nullable String name);
 
-        FromPromptBuilder withInputParameters(List<InputVariable> inputVariables);
+        FromPromptBuilder withInputParameters(
+            @Nullable List<InputVariable> inputVariables);
 
-        FromPromptBuilder withPromptTemplate(PromptTemplate promptTemplate);
+        FromPromptBuilder withPromptTemplate(
+            @Nullable PromptTemplate promptTemplate);
 
         FromPromptBuilder withExecutionSettings(
+            @Nullable
             Map<String, PromptExecutionSettings> executionSettings);
 
         FromPromptBuilder withDefaultExecutionSettings(
+            @Nullable
             PromptExecutionSettings executionSettings);
 
-        FromPromptBuilder withDescription(String description);
+        FromPromptBuilder withDescription(@Nullable String description);
 
-        FromPromptBuilder withTemplate(String template);
+        FromPromptBuilder withTemplate(@Nullable String template);
 
         KernelFunction build();
 
         FromPromptBuilder withTemplateFormat(String templateFormat);
 
-        FromPromptBuilder withOutputVariable(OutputVariable outputVariable);
+        FromPromptBuilder withOutputVariable(@Nullable OutputVariable outputVariable);
 
-        FromPromptBuilder withPromptTemplateFactory(PromptTemplateFactory promptTemplateFactory);
+        FromPromptBuilder withPromptTemplateFactory(
+            @Nullable PromptTemplateFactory promptTemplateFactory);
     }
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/KernelFunctionMetadata.java

@@ -5,15 +5,17 @@ import com.microsoft.semantickernel.plugin.KernelReturnParameterMetadata;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import javax.annotation.Nullable;
 
 public class KernelFunctionMetadata {
 
     /// <summary>The name of the function.</summary>
     private final String name;
     /// <summary>The description of the function.</summary>
+    @Nullable
     private final String description;
     /// <summary>The function's parameters.</summary>
-    private final List<KernelParameterMetadata> parameters;
+    private final List<KernelParameterMetadata<?>> parameters;
 
 
     /// <summary>The function's return parameter.</summary>
@@ -22,12 +24,19 @@ public class KernelFunctionMetadata {
 
     public KernelFunctionMetadata(
         String name,
+        @Nullable
         String description,
-        List<KernelParameterMetadata> parameters,
+        @Nullable
+        List<KernelParameterMetadata<?>> parameters,
         KernelReturnParameterMetadata<?> returnParameter) {
         this.name = name;
         this.description = description;
-        this.parameters = new ArrayList<>(parameters);
+        if (parameters == null) {
+            this.parameters = new ArrayList<>();
+        } else {
+            this.parameters = new ArrayList<>(parameters);
+        }
+
         this.returnParameter = returnParameter;
     }
 
@@ -35,10 +44,11 @@ public class KernelFunctionMetadata {
         return name;
     }
 
-    public List<KernelParameterMetadata> getParameters() {
+    public List<KernelParameterMetadata<?>> getParameters() {
         return Collections.unmodifiableList(parameters);
     }
 
+    @Nullable
     public String getDescription() {
         return description;
     }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/MethodDetails.java

@@ -6,21 +6,24 @@ import com.microsoft.semantickernel.semanticfunctions.KernelFunctionFromMethod.I
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import javax.annotation.Nullable;
 
 public class MethodDetails {
 
     private final String name;
+    @Nullable
     private final String description;
     private final ImplementationFunc function;
-    private final List<KernelParameterMetadata> parameters;
-    private final KernelReturnParameterMetadata returnParameter;
+    private final List<KernelParameterMetadata<?>> parameters;
+    private final KernelReturnParameterMetadata<?> returnParameter;
 
     public MethodDetails(
         String name,
+        @Nullable
         String description,
         ImplementationFunc function,
-        List<KernelParameterMetadata> parameters,
-        KernelReturnParameterMetadata returnParameter) {
+        List<KernelParameterMetadata<?>> parameters,
+        KernelReturnParameterMetadata<?> returnParameter) {
         this.name = name;
         this.description = description;
         this.function = function;
@@ -32,6 +35,7 @@ public class MethodDetails {
         return name;
     }
 
+    @Nullable
     public String getDescription() {
         return description;
     }
@@ -40,11 +44,11 @@ public class MethodDetails {
         return function;
     }
 
-    public List<KernelParameterMetadata> getParameters() {
+    public List<KernelParameterMetadata<?>> getParameters() {
         return Collections.unmodifiableList(parameters);
     }
 
-    public KernelReturnParameterMetadata getReturnParameter() {
+    public KernelReturnParameterMetadata<?> getReturnParameter() {
         return returnParameter;
     }
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/contextvariables/ContextVariable.java

@@ -1,23 +1,148 @@
 // Copyright (c) Microsoft. All rights reserved.
 package com.microsoft.semantickernel.orchestration.contextvariables;
 
+import com.microsoft.semantickernel.exceptions.SKException;
+import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypeConverter.NoopConverter;
+import javax.annotation.Nullable;
+
 public class ContextVariable<T> {
 
     private final ContextVariableType<T> type;
+
+    @Nullable
     private final T value;
 
-    public ContextVariable(ContextVariableType<T> type, T value) {
+    public ContextVariable(ContextVariableType<T> type,
+        @Nullable T value) {
         this.type = type;
         this.value = value;
     }
 
+    public static <T> ContextVariable<T> of(Class<T> type, @Nullable T t) {
+        if (t == null) {
+            return new ContextVariable<>(
+                ContextVariableTypes.getDefaultVariableTypeForClass(type),
+                null);
+        }
+
+        return of(t);
+    }
+
+    public static ContextVariable<?> untypedOf(
+        @Nullable Object value,
+        Class<?> clazz) {
+        ContextVariableType<?> type = ContextVariableTypes.getDefaultVariableTypeForClass(clazz);
+        return new ContextVariable(type, value);
+    }
+
+    public static ContextVariable<?> untypedOf(
+        @Nullable Object value,
+        ContextVariableTypeConverter<?> converter) {
+        ContextVariableType<?> type = new ContextVariableType(converter, converter.getType());
+        return new ContextVariable(type, value);
+    }
+
+    public static <T, U> ContextVariable<T> convert(
+        @Nullable
+        U it,
+        Class<T> requestedResultType) {
+        return convert(
+            it,
+            requestedResultType,
+            ContextVariableTypes.DEFAULT_TYPES
+        );
+    }
+
+    public static <T, U> ContextVariable<T> convert(
+        @Nullable
+        U it,
+        Class<T> requestedResultType,
+        ContextVariableTypes contextVariableTypes) {
+        if (it == null) {
+            return new ContextVariable<>(
+                contextVariableTypes.getVariableTypeForClass(requestedResultType),
+                null);
+        }
+
+        if (requestedResultType.isAssignableFrom(it.getClass())) {
+            try {
+                return ContextVariable.of(requestedResultType, requestedResultType.cast(it));
+            } catch (Exception e) {
+                return new ContextVariable<>(
+                    new ContextVariableType<>(
+                        new NoopConverter<>(requestedResultType),
+                        requestedResultType
+                    ),
+                    requestedResultType.cast(it)
+                );
+            }
+        }
+
+        ContextVariableType<T> requestedResultTypeVariable;
+
+        try {
+            requestedResultTypeVariable = contextVariableTypes.getVariableTypeForClass(
+                requestedResultType);
+        } catch (Exception e) {
+            throw new SKException("Unable to find variable type for " + requestedResultType, e);
+        }
+
+        ContextVariableType<U> typeOfActualReturnedType;
+
+        try {
+            // First try to convert from type ? to T using the converter of ? and see if it can convert it to T.
+            typeOfActualReturnedType = contextVariableTypes.getVariableTypeForClass(
+                (Class<U>) it.getClass());
+        } catch (Exception e) {
+            typeOfActualReturnedType = contextVariableTypes.getVariableTypeForSuperClass(
+                (Class<U>) it.getClass());
+        }
+
+        if (typeOfActualReturnedType != null) {
+            // Try the to object
+            T converted = typeOfActualReturnedType.getConverter().toObject(it, requestedResultType);
+
+            if (converted != null) {
+                return contextVariableTypes.getVariableTypeForClass(requestedResultType)
+                    .of(converted);
+            }
+
+            if (requestedResultType.isAssignableFrom(String.class)) {
+                // Try using toPromptString
+                String str = typeOfActualReturnedType.getConverter()
+                    .toPromptString(typeOfActualReturnedType.getClazz().cast(it));
+
+                return requestedResultTypeVariable.of(str);
+            }
+        }
+
+        // Try getting a converter of type T and see if it can convert ? to T.
+        if (requestedResultTypeVariable != null) {
+            // Try using from object
+            T result = requestedResultTypeVariable.getConverter().fromObject(it);
+            if (result != null) {
+                return requestedResultTypeVariable.of(result);
+            }
+
+            if (requestedResultType.equals(String.class)) {
+                // Try using from prompt string
+                return requestedResultTypeVariable.of(
+                    requestedResultTypeVariable.getConverter().fromPromptString((String) it));
+            }
+        }
+
+        throw new SKException("Unable to convert " + it.getClass() + " to " + requestedResultType);
+    }
+
+    @Nullable
     public T getValue() {
         return value;
     }
 
+    @Nullable
     public <U> U getValue(Class<U> clazz) {
-        if (clazz.isAssignableFrom(value.getClass())) {
-            return (U) value;
+        if (value == null || clazz.isAssignableFrom(value.getClass())) {
+            return clazz.cast(value);
         } else {
             throw new RuntimeException("Cannot cast " + value.getClass() + " to " + clazz);
         }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/contextvariables/ContextVariableType.java

@@ -1,5 +1,7 @@
 package com.microsoft.semantickernel.orchestration.contextvariables;
 
+import javax.annotation.Nullable;
+
 public class ContextVariableType<T> {
 
     private final ContextVariableTypeConverter<T> contextVariableTypeConverter;
@@ -26,10 +28,15 @@ public class ContextVariableType<T> {
      * @param it The object to convert.
      * @return A context variable of this type.
      */
-    public ContextVariable<T> of(Object it) {
-        if (getClazz().isAssignableFrom(it.getClass())) {
-            return ContextVariable.of((T) it, getConverter());
+    public ContextVariable<T> of(@Nullable Object it) {
+        if (it == null) {
+            return ContextVariable.of(clazz, clazz.cast(null));
         }
-        return ContextVariable.of(getConverter().fromObject(it));
+
+        if (clazz.isAssignableFrom(it.getClass())) {
+            return ContextVariable.of(clazz.cast(it), getConverter());
+        }
+        ContextVariableTypeConverter<T> converter = getConverter();
+        return ContextVariable.of(converter.getType(), converter.fromObject(it));
     }
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/contextvariables/ContextVariableTypeConverter.java

@@ -79,10 +79,14 @@ public class ContextVariableTypeConverter<T> {
         this.toObjects = new ArrayList<>(toObjects);
     }
 
-    
+
     @Nullable
     @SuppressWarnings("unchecked")
-    public <U> U toObject(Object t, Class<U> clazz) {
+    public <U> U toObject(@Nullable Object t, Class<U> clazz) {
+        if (t == null) {
+            return null;
+        }
+
         Optional<Converter<T, ?>> converter = toObjects
             .stream()
             .filter(c -> c.getTargetType().equals(clazz))
@@ -106,14 +110,14 @@ public class ContextVariableTypeConverter<T> {
     }
 
     @Nullable
-    public T fromObject(Object s) {
+    public T fromObject(@Nullable Object s) {
         if (s == null) {
             return null;
         }
         return fromObject.apply(s);
     }
 
-    public String toPromptString(T t) {
+    public String toPromptString(@Nullable T t) {
         if (t == null) {
             return "";
         }
@@ -121,7 +125,7 @@ public class ContextVariableTypeConverter<T> {
     }
 
     @Nullable
-    public T fromPromptString(String t) {
+    public T fromPromptString(@Nullable String t) {
         if (t == null) {
             return null;
         }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/contextvariables/ContextVariableTypes.java

@@ -5,6 +5,7 @@ import com.microsoft.semantickernel.orchestration.contextvariables.converters.Ch
 import com.microsoft.semantickernel.orchestration.contextvariables.converters.ChatHistoryVariableContextVariableTypeConverter;
 import com.microsoft.semantickernel.orchestration.contextvariables.converters.CompletionUsageContextVariableTypeConverter;
 import com.microsoft.semantickernel.orchestration.contextvariables.converters.DateTimeContextVariableTypeConverter;
+import com.microsoft.semantickernel.orchestration.contextvariables.converters.InstantContextVariableTypeConverter;
 import com.microsoft.semantickernel.orchestration.contextvariables.converters.NumberVariableContextVariableTypeConverter;
 import com.microsoft.semantickernel.orchestration.contextvariables.converters.StringVariableContextVariableTypeConverter;
 import com.microsoft.semantickernel.orchestration.contextvariables.converters.VoidVariableContextVariableTypeConverter;
@@ -12,6 +13,7 @@ import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import javax.annotation.Nullable;
 
 public class ContextVariableTypes {
 
@@ -24,7 +26,9 @@ public class ContextVariableTypes {
             new ChatHistoryVariableContextVariableTypeConverter(),
             new StringVariableContextVariableTypeConverter(),
             new VoidVariableContextVariableTypeConverter(),
+            new ContextVariableTypeConverter<>(void.class, s -> null, s -> null, s -> null),
             new DateTimeContextVariableTypeConverter(),
+            new InstantContextVariableTypeConverter(),
             new CompletionUsageContextVariableTypeConverter(),
 
             new NumberVariableContextVariableTypeConverter<>(Byte.class, Byte::parseByte),
@@ -64,8 +68,9 @@ public class ContextVariableTypes {
                 contextVariableTypeConverter.getType()));
     }
 
+    @Nullable
     @SuppressWarnings("unchecked")
-    public static <T> T convert(Object s, Class<T> clazz) {
+    public static <T> T convert(@Nullable Object s, Class<T> clazz) {
         if (s instanceof ContextVariable && ((ContextVariable<?>) s).getType().getClazz()
             .isAssignableFrom(clazz)) {
             return ((ContextVariable<T>) s).getValue();
@@ -92,10 +97,29 @@ public class ContextVariableTypes {
         return (ContextVariableType<T>) variableTypes
             .values()
             .stream()
-            .filter(c -> c.getClazz().isAssignableFrom(aClass))
+            .filter(c -> {
+                return c.getClazz().isAssignableFrom(aClass);
+            })
             .findFirst()
             .orElseThrow(
                 () -> new RuntimeException("Unknown context variable type: " + aClass.getName()));
+    }
 
+    public <T> ContextVariableType<T> getVariableTypeForSuperClass(Class<T> aClass) {
+        ContextVariableType<?> contextVariableType = variableTypes.get(aClass);
+
+        if (contextVariableType != null) {
+            return (ContextVariableType<T>) contextVariableType;
+        }
+
+        return (ContextVariableType<T>) variableTypes
+            .values()
+            .stream()
+            .filter(c -> {
+                return aClass.isAssignableFrom(c.getClazz());
+            })
+            .findFirst()
+            .orElseThrow(
+                () -> new RuntimeException("Unknown context variable type: " + aClass.getName()));
     }
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/contextvariables/DefaultKernelArguments.java

@@ -90,11 +90,6 @@ public class DefaultKernelArguments implements KernelArguments, WritableKernelAr
         return setVariable(MAIN_KEY, content);
     }
 
-    @Override
-    public KernelArguments update(String content) {
-        return null;
-    }
-
     public DefaultKernelArguments update(@NonNull DefaultKernelArguments newData) {
         return update(newData, true);
     }
@@ -198,6 +193,7 @@ public class DefaultKernelArguments implements KernelArguments, WritableKernelAr
     }
 
     @Override
+    @Nullable
     public ContextVariable<?> get(Object key) {
         return variables.get(key);
     }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/contextvariables/NullContextVariable.java

@@ -0,0 +1,13 @@
+package com.microsoft.semantickernel.orchestration.contextvariables;
+
+import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypeConverter.NoopConverter;
+
+public class NullContextVariable<T> extends ContextVariable<T> {
+
+    public NullContextVariable(Class<T> type) {
+        super(new ContextVariableType<>(
+            new NoopConverter<>(type),
+            type
+        ), null);
+    }
+}

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/contextvariables/WritableKernelArguments.java

@@ -29,8 +29,6 @@ public interface WritableKernelArguments extends KernelArguments {
      */
     KernelArguments update(ContextVariable<?> content);
 
-    KernelArguments update(String content);
-
     /**
      * Updates the variables merging or overwriting in the new values.
      *

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/contextvariables/converters/DateTimeContextVariableTypeConverter.java

@@ -1,8 +1,10 @@
 package com.microsoft.semantickernel.orchestration.contextvariables.converters;
 
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypeConverter;
+import java.time.Instant;
 import java.time.OffsetDateTime;
 import java.time.ZonedDateTime;
+import java.util.Arrays;
 
 public class DateTimeContextVariableTypeConverter extends
     ContextVariableTypeConverter<OffsetDateTime> {
@@ -21,6 +23,14 @@ public class DateTimeContextVariableTypeConverter extends
             Object::toString,
             o -> {
                 return ZonedDateTime.parse(o).toOffsetDateTime();
-            });
+            },
+            Arrays.asList(
+                new DefaultConverter<OffsetDateTime, Instant>(OffsetDateTime.class, Instant.class) {
+                    @Override
+                    public Instant toObject(OffsetDateTime offsetDateTime) {
+                        return offsetDateTime.toInstant();
+                    }
+                }
+            ));
     }
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/contextvariables/converters/InstantContextVariableTypeConverter.java

@@ -0,0 +1,26 @@
+package com.microsoft.semantickernel.orchestration.contextvariables.converters;
+
+import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypeConverter;
+import java.time.Instant;
+import java.time.OffsetDateTime;
+
+public class InstantContextVariableTypeConverter extends
+    ContextVariableTypeConverter<Instant> {
+
+    public InstantContextVariableTypeConverter() {
+        super(
+            Instant.class,
+            s -> {
+                if (s instanceof String) {
+                    return Instant.parse((String) s);
+                } else if (s instanceof OffsetDateTime) {
+                    return ((OffsetDateTime) s).toInstant();
+                }
+                return null;
+            },
+            Object::toString,
+            o -> {
+                return Instant.parse(o);
+            });
+    }
+}

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/orchestration/contextvariables/converters/NumberVariableContextVariableTypeConverter.java

@@ -1,11 +1,10 @@
 package com.microsoft.semantickernel.orchestration.contextvariables.converters;
 
-import java.util.function.Function;
-
-import javax.annotation.Nullable;
+import static com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypes.convert;
 
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypeConverter;
-import static com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypes.convert;
+import java.util.function.Function;
+import javax.annotation.Nullable;
 
 public class NumberVariableContextVariableTypeConverter<T extends Number> extends
     ContextVariableTypeConverter<T> {
@@ -21,7 +20,11 @@ public class NumberVariableContextVariableTypeConverter<T extends Number> extend
 
     @Override
     @Nullable
-    public <U> U toObject(Object t, Class<U> clazz) {
+    public <U> U toObject(@Nullable Object t, Class<U> clazz) {
+        if (t == null) {
+            return null;
+        }
+
         // Let the parent class have a crack at it first
         // since someone may have installed a special converter. 
         U obj = super.toObject(t, clazz);
@@ -35,12 +38,13 @@ public class NumberVariableContextVariableTypeConverter<T extends Number> extend
         }
         return null;
     }
- 
+
     @Override
-    public T fromObject(Object s) {
+    @Nullable
+    public T fromObject(@Nullable Object s) {
         T obj = super.fromObject(s);
         if (obj != null) {
-            return obj; 
+            return obj;
         }
         if (s instanceof String) {
             return fromPromptString((String) s);
@@ -49,11 +53,12 @@ public class NumberVariableContextVariableTypeConverter<T extends Number> extend
     }
 
     @Override
-    public T fromPromptString(String s) {
+    @Nullable
+    public T fromPromptString(@Nullable String s) {
         if (s != null && !s.isEmpty()) {
             return super.fromPromptString(s);
         }
-        return null; 
+        return null;
     }
 
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/plugin/KernelFunctionFactory.java

@@ -1,8 +1,8 @@
 package com.microsoft.semantickernel.plugin;
 
 import com.microsoft.semantickernel.orchestration.KernelFunction;
-import com.microsoft.semantickernel.semanticfunctions.KernelFunctionFromMethod;
 import com.microsoft.semantickernel.orchestration.PromptExecutionSettings;
+import com.microsoft.semantickernel.semanticfunctions.KernelFunctionFromMethod;
 import com.microsoft.semantickernel.semanticfunctions.KernelFunctionFromPrompt;
 import com.microsoft.semantickernel.semanticfunctions.KernelPromptTemplateFactory;
 import com.microsoft.semantickernel.semanticfunctions.PromptTemplate;
@@ -16,30 +16,6 @@ import javax.annotation.Nullable;
 
 public class KernelFunctionFactory {
 
-    /// <summary>
-    /// Creates a <see cref="KernelFunction"/> instance for a method, specified via a delegate.
-    /// </summary>
-    /// <param name="method">The method to be represented via the created <see cref="KernelFunction"/>.</param>
-    /// <param name="functionName">Optional function name. If null, it will default to one derived from the method represented by <paramref name="method"/>.</param>
-    /// <param name="description">Optional description of the method. If null, it will default to one derived from the method represented by <paramref name="method"/>, if possible (e.g. via a <see cref="DescriptionAttribute"/> on the method).</param>
-    /// <param name="parameters">Optional parameter descriptions. If null, it will default to one derived from the method represented by <paramref name="method"/>.</param>
-    /// <param name="returnParameter">Optional return parameter description. If null, it will default to one derived from the method represented by <paramref name="method"/>.</param>
-    /// <param name="loggerFactory">The <see cref="ILoggerFactory"/> to use for logging. If null, no logging will be performed.</param>
-    /// <returns>The created <see cref="KernelFunction"/> wrapper for <paramref name="method"/>.</returns>
-    public static KernelFunction createFromMethod(
-        Method method,
-        @Nullable String functionName,
-        @Nullable String description,
-        List<KernelParameterMetadata> parameters,
-        KernelReturnParameterMetadata<?> returnParameter) {
-        return createFromMethod(
-            method,
-            null,
-            functionName,
-            description,
-            parameters,
-            returnParameter);
-    }
 
     /// <summary>
     /// Creates a <see cref="KernelFunction"/> instance for a method, specified via an <see cref="MethodInfo"/> instance
@@ -55,10 +31,10 @@ public class KernelFunctionFactory {
     /// <returns>The created <see cref="KernelFunction"/> wrapper for <paramref name="method"/>.</returns>
     public static KernelFunction createFromMethod(
         Method method,
-        @Nullable Object target,
+        Object target,
         @Nullable String functionName,
         @Nullable String description,
-        @Nullable List<KernelParameterMetadata> parameters,
+        @Nullable List<KernelParameterMetadata<?>> parameters,
         @Nullable KernelReturnParameterMetadata<?> returnParameter) {
         return KernelFunctionFromMethod.create(method, target, functionName, description,
             parameters, returnParameter);
@@ -87,8 +63,8 @@ public class KernelFunctionFactory {
      * @param templateFormat        The template format of {@code promptTemplate}. This must be
      *                              provided if {@code promptTemplateFactory} is not null.
      * @param promptTemplateFactory The {@link PromptTemplateFactory} to use when interpreting the
-     *                              {@code promptTemplate} into a {@link IPromptTemplate}. If null,
-     *                              a default factory will be used.
+     *                              {@code promptTemplate} into a {@link PromptTemplate}. If null, a
+     *                              default factory will be used.
      * @return The created {@link KernelFunction} for invoking the prompt.
      */
     public static KernelFunction createFromPrompt(
@@ -129,9 +105,12 @@ public class KernelFunctionFactory {
     }
 
     private static Map<String, PromptExecutionSettings> createSettingsDictionary(
+        @Nullable
         PromptExecutionSettings executionSettings) {
         HashMap<String, PromptExecutionSettings> map = new HashMap<>();
-        map.put("default", executionSettings);
+        if (executionSettings != null) {
+            map.put("default", executionSettings);
+        }
         return map;
     }
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/plugin/KernelParameterMetadata.java

@@ -1,20 +1,27 @@
 package com.microsoft.semantickernel.plugin;
 
+import javax.annotation.Nullable;
+
 public class KernelParameterMetadata<T> {
 
     /// <summary>The name of the parameter.</summary>
     private final String name;
     /// <summary>The description of the parameter.</summary>
+    @Nullable
     private final String description;
+    @Nullable
     private final String defaultValue;
     private final boolean isRequired;
     private final Class<T> parameterType;
 
     public KernelParameterMetadata(
         String name,
+        @Nullable
         String description,
         Class<T> parameterType,
-        String defaultValue, boolean isRequired) {
+        @Nullable
+        String defaultValue,
+        boolean isRequired) {
         this.name = name;
         this.description = description;
         this.defaultValue = defaultValue;
@@ -26,10 +33,12 @@ public class KernelParameterMetadata<T> {
         return name;
     }
 
+    @Nullable
     public String getDescription() {
         return description;
     }
 
+    @Nullable
     public String getDefaultValue() {
         return defaultValue;
     }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/plugin/KernelPlugin.java

@@ -5,15 +5,20 @@ import com.microsoft.semantickernel.orchestration.contextvariables.CaseInsensiti
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.Map;
+import javax.annotation.Nullable;
 
 public class KernelPlugin implements Iterable<KernelFunction> {
 
     private final String name;
+    @Nullable
     private final String description;
 
     private final CaseInsensitiveMap<KernelFunction> functions;
 
-    public KernelPlugin(String name, String description,
+    public KernelPlugin(
+        String name,
+        @Nullable
+        String description,
         Map<String, KernelFunction> plugins) {
         this.name = name;
         this.description = description;
@@ -23,10 +28,15 @@ public class KernelPlugin implements Iterable<KernelFunction> {
         }
     }
 
+    public void addFunction(KernelFunction function) {
+        functions.put(function.getName(), function);
+    }
+
     public Map<String, KernelFunction> getFunctions() {
         return Collections.unmodifiableMap(functions);
     }
 
+    @Nullable
     public KernelFunction get(String functionName) {
         return functions.get(functionName);
     }
@@ -40,6 +50,7 @@ public class KernelPlugin implements Iterable<KernelFunction> {
         return name;
     }
 
+    @Nullable
     public String getDescription() {
         return description;
     }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/plugin/KernelPluginFactory.java

@@ -6,7 +6,7 @@ import com.microsoft.semantickernel.orchestration.KernelFunction;
 import com.microsoft.semantickernel.orchestration.contextvariables.CaseInsensitiveMap;
 import com.microsoft.semantickernel.plugin.annotations.DefineKernelFunction;
 import com.microsoft.semantickernel.plugin.annotations.KernelFunctionParameter;
-import com.microsoft.semantickernel.semanticfunctions.KernelFunctionFromPrompt.Builder;
+import com.microsoft.semantickernel.semanticfunctions.KernelFunctionFromPrompt;
 import com.microsoft.semantickernel.semanticfunctions.KernelPromptTemplateFactory;
 import com.microsoft.semantickernel.semanticfunctions.PromptTemplate;
 import com.microsoft.semantickernel.semanticfunctions.PromptTemplateConfig;
@@ -46,13 +46,13 @@ public class KernelPluginFactory {
     /// Public methods decorated with <see cref="KernelFunctionAttribute"/> will be included in the plugin.
     /// Attributed methods must all have different names; overloads are not supported.
     /// </remarks>
-    public static KernelPlugin createFromObject(Object target, @Nullable String pluginName) {
+    public static KernelPlugin createFromObject(Object target, String pluginName) {
         List<KernelFunction> methods = Arrays.stream(target.getClass().getMethods())
             .filter(method -> method.isAnnotationPresent(DefineKernelFunction.class))
             .map(method -> {
                 DefineKernelFunction annotation = method.getAnnotation(DefineKernelFunction.class);
                 Class<?> returnType = getReturnType(annotation, method);
-                KernelReturnParameterMetadata kernelReturnParameterMetadata = new KernelReturnParameterMetadata(
+                KernelReturnParameterMetadata<?> kernelReturnParameterMetadata = new KernelReturnParameterMetadata<>(
                     annotation.returnDescription(),
                     returnType);
 
@@ -75,10 +75,9 @@ public class KernelPluginFactory {
             returnType = method.getReturnType();
 
             if (Publisher.class.isAssignableFrom(returnType)) {
-                LOGGER.warn(
-                    "For method: " + method.getDeclaringClass().getName() + "." + method.getName()
-                        + ", this is an async method, if a return type is required, please specify it in the annotation. Defaulting to Void return type");
-                returnType = Void.class;
+                throw new SKException(
+                    "Method: " + method.getDeclaringClass().getName() + "." + method.getName()
+                        + ", this is an async method, It is required to add an annotation to specify the return type");
             }
         } else {
             try {
@@ -109,7 +108,8 @@ public class KernelPluginFactory {
     /// <exception cref="ArgumentException"><paramref name="pluginName"/> is an invalid plugin name.</exception>
     /// <exception cref="ArgumentNullException"><paramref name="functions"/> contains a null function.</exception>
     /// <exception cref="ArgumentException"><paramref name="functions"/> contains two functions with the same name.</exception>
-    public static KernelPlugin createFromFunctions(String pluginName,
+    public static KernelPlugin createFromFunctions(
+        String pluginName,
         @Nullable List<KernelFunction> functions) {
         return createFromFunctions(pluginName, null, functions);
     }
@@ -132,15 +132,19 @@ public class KernelPluginFactory {
     }
 
 
-    private static List<KernelParameterMetadata> getParameters(Method method) {
+    private static List<KernelParameterMetadata<?>> getParameters(Method method) {
         return Arrays.stream(method.getParameters())
             .filter(parameter -> parameter.isAnnotationPresent(KernelFunctionParameter.class))
             .map(parameter -> {
                 KernelFunctionParameter annotation = parameter.getAnnotation(
                     KernelFunctionParameter.class);
 
-                return new KernelParameterMetadata(annotation.name(), annotation.description(),
-                    null, annotation.defaultValue(), annotation.required());
+                return new KernelParameterMetadata<>(
+                    annotation.name(),
+                    annotation.description(),
+                    annotation.type(),
+                    annotation.defaultValue(),
+                    annotation.required());
             }).collect(Collectors.toList());
     }
 
@@ -176,8 +180,8 @@ public class KernelPluginFactory {
                     // configuration, unable to parse {configPath}");
                 }
 
-                KernelFunction plugin = getKernelFunction(pluginDirectoryName,
-                    promptTemplateFactory, configPath, promptPath);
+                KernelFunction plugin = getKernelFunction(promptTemplateFactory, configPath,
+                    promptPath);
 
                 plugins.put(dir.getName(), plugin);
             } catch (IOException e) {
@@ -192,8 +196,10 @@ public class KernelPluginFactory {
         );
     }
 
-    private static KernelFunction getKernelFunction(String pluginDirectoryName,
-        PromptTemplateFactory promptTemplateFactory, File configPath, File promptPath)
+    private static KernelFunction getKernelFunction(
+        PromptTemplateFactory promptTemplateFactory,
+        File configPath,
+        File promptPath)
         throws IOException {
         PromptTemplateConfig config = new ObjectMapper().readValue(configPath,
             PromptTemplateConfig.class);
@@ -202,11 +208,13 @@ public class KernelPluginFactory {
         String template = new String(Files.readAllBytes(promptPath.toPath()),
             Charset.defaultCharset());
 
-        return getKernelFunction(pluginDirectoryName, promptTemplateFactory, config, template);
+        return getKernelFunction(promptTemplateFactory, config, template);
     }
 
-    private static KernelFunction getKernelFunction(String pluginDirectoryName,
-        PromptTemplateFactory promptTemplateFactory, PromptTemplateConfig config, String template) {
+    private static KernelFunction getKernelFunction(
+        PromptTemplateFactory promptTemplateFactory,
+        PromptTemplateConfig config,
+        String template) {
         PromptTemplate promptTemplate;
 
         if (promptTemplateFactory != null) {
@@ -215,10 +223,12 @@ public class KernelPluginFactory {
             promptTemplate = new KernelPromptTemplateFactory().tryCreate(config);
         }
 
-        return new Builder().withName(config.getName()).withDescription(config.getDescription())
+        return new KernelFunctionFromPrompt.Builder()
+            .withName(config.getName())
+            .withDescription(config.getDescription())
             .withExecutionSettings(config.getExecutionSettings())
-            .withInputParameters(config.getInputVariables()
-            ).withPromptTemplate(promptTemplate)
+            .withInputParameters(config.getInputVariables())
+            .withPromptTemplate(promptTemplate)
             .withTemplate(template)
             .withTemplateFormat(config.getTemplateFormat())
             .withOutputVariable(config.getOutputVariable())
@@ -226,9 +236,13 @@ public class KernelPluginFactory {
             .build();
     }
 
-    public static KernelPlugin importPluginFromResourcesDirectory(String parentDirectory,
-        String pluginDirectoryName, String functionName,
-        PromptTemplateFactory promptTemplateFactory, @Nullable Class<?> clazz) {
+    @Nullable
+    public static KernelPlugin importPluginFromResourcesDirectory(
+        String parentDirectory,
+        String pluginDirectoryName,
+        String functionName,
+        PromptTemplateFactory promptTemplateFactory,
+        Class<?> clazz) {
 
         String template = getTemplatePrompt(parentDirectory, pluginDirectoryName, functionName,
             clazz);
@@ -236,7 +250,12 @@ public class KernelPluginFactory {
         PromptTemplateConfig promptTemplateConfig = getPromptTemplateConfig(parentDirectory,
             pluginDirectoryName, functionName, clazz);
 
-        KernelFunction function = getKernelFunction(pluginDirectoryName, promptTemplateFactory,
+        if (promptTemplateConfig == null) {
+            LOGGER.warn("Unable to load prompt template config for " + functionName + " in "
+                + pluginDirectoryName);
+            return null;
+        }
+        KernelFunction function = getKernelFunction(promptTemplateFactory,
             promptTemplateConfig, template);
 
         HashMap<String, KernelFunction> plugins = new HashMap<>();
@@ -250,8 +269,11 @@ public class KernelPluginFactory {
         );
     }
 
-    private static String getTemplatePrompt(String pluginDirectory, String pluginName,
-        String functionName, @Nullable Class clazz) {
+    private static String getTemplatePrompt(
+        String pluginDirectory,
+        String pluginName,
+        String functionName,
+        Class<?> clazz) {
         String promptFileName =
             pluginDirectory + File.separator + pluginName + File.separator + functionName
                 + File.separator + PROMPT_FILE;
@@ -265,14 +287,17 @@ public class KernelPluginFactory {
         }
     }
 
-    private static String getFileContents(String file, @Nullable Class clazz)
+    private static String getFileContents(String file, Class<?> clazz)
         throws FileNotFoundException {
         return EmbeddedResourceLoader.readFile(file, clazz, ResourceLocation.CLASSPATH_ROOT,
             ResourceLocation.CLASSPATH, ResourceLocation.FILESYSTEM);
     }
 
-    private static PromptTemplateConfig getPromptTemplateConfig(String pluginDirectory,
-        String pluginName, String functionName, @Nullable Class clazz) {
+    @Nullable
+    private static PromptTemplateConfig getPromptTemplateConfig(
+        String pluginDirectory,
+        String pluginName, String functionName,
+        Class<?> clazz) {
         String configFileName =
             pluginDirectory + File.separator + pluginName + File.separator + functionName
                 + File.separator + CONFIG_FILE;

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/plugin/KernelReturnParameterMetadata.java

@@ -1,17 +1,22 @@
 package com.microsoft.semantickernel.plugin;
 
+import javax.annotation.Nullable;
+
 public class KernelReturnParameterMetadata<T> {
 
+    @Nullable
     private final String description;
     private final Class<T> parameterType;
 
     public KernelReturnParameterMetadata(
+        @Nullable
         String description,
         Class<T> parameterType) {
         this.description = description;
         this.parameterType = parameterType;
     }
 
+    @Nullable
     public String getDescription() {
         return description;
     }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/AggregatorPromptTemplateFactory.java

@@ -1,21 +1,25 @@
 package com.microsoft.semantickernel.semanticfunctions;
 
-import reactor.util.annotation.NonNull;
-
 import java.util.ArrayList;
 import java.util.List;
+import reactor.util.annotation.NonNull;
 
 public class AggregatorPromptTemplateFactory implements PromptTemplateFactory {
+
     private final List<PromptTemplateFactory> templateFactories;
+
     public AggregatorPromptTemplateFactory(List<PromptTemplateFactory> templateFactories) {
         this.templateFactories = new ArrayList<>(templateFactories);
     }
+
     @Override
     public PromptTemplate tryCreate(@NonNull PromptTemplateConfig templateConfig) {
         for (PromptTemplateFactory factory : templateFactories) {
             try {
                 return factory.tryCreate(templateConfig);
-            } catch (UnknownTemplateFormatException ignored) { }
+            } catch (UnknownTemplateFormatException ignored) {
+                // No-op
+            }
         }
 
         throw new UnknownTemplateFormatException(templateConfig.getTemplateFormat());

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/HandlebarsPromptTemplateFactory.java

@@ -1,17 +1,18 @@
 package com.microsoft.semantickernel.semanticfunctions;
 
 import com.microsoft.semantickernel.templateengine.handlebars.HandlebarsPromptTemplate;
-import reactor.util.annotation.NonNull;
-
 import java.util.Locale;
+import reactor.util.annotation.NonNull;
 
 public class HandlebarsPromptTemplateFactory implements PromptTemplateFactory {
 
     public static final String HANDLEBARS_TEMPLATE_FORMAT = "handlebars";
 
+    @Override
     public PromptTemplate tryCreate(@NonNull PromptTemplateConfig templateConfig) {
         if (templateConfig.getTemplateFormat() != null &&
-                HANDLEBARS_TEMPLATE_FORMAT.equals(templateConfig.getTemplateFormat().toLowerCase(Locale.ROOT))) {
+            HANDLEBARS_TEMPLATE_FORMAT.equals(
+                templateConfig.getTemplateFormat().toLowerCase(Locale.ROOT))) {
             return new HandlebarsPromptTemplate(templateConfig);
         }
 

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/InputVariable.java

@@ -1,6 +1,8 @@
 package com.microsoft.semantickernel.semanticfunctions;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
+import com.microsoft.semantickernel.exceptions.SKException;
+import javax.annotation.Nullable;
 
 public class InputVariable {
 
@@ -10,27 +12,31 @@ public class InputVariable {
     @JsonProperty("type")
     private String type;
 
+    @Nullable
     @JsonProperty("description")
     private String description;
 
     @JsonProperty("default")
+    @Nullable
     private String defaultValue;
 
     @JsonProperty("is_required")
     private boolean isRequired;
 
-    public InputVariable() {
-    }
-
-    public InputVariable(
-        String name) {
+    public InputVariable(String name) {
         this.name = name;
+        this.type = String.class.getName();
+        this.description = null;
+        this.defaultValue = null;
+        this.isRequired = true;
     }
 
     public InputVariable(
         String name,
         String type,
+        @Nullable
         String description,
+        @Nullable
         String defaultValue,
         boolean isRequired) {
         this.name = name;
@@ -56,6 +62,7 @@ public class InputVariable {
         this.type = type;
     }
 
+    @Nullable
     public String getDescription() {
         return description;
     }
@@ -64,6 +71,7 @@ public class InputVariable {
         this.description = description;
     }
 
+    @Nullable
     public String getDefaultValue() {
         return defaultValue;
     }
@@ -79,4 +87,14 @@ public class InputVariable {
     public void setRequired(boolean required) {
         isRequired = required;
     }
+
+    public Class<?> getTypeClass() {
+        try {
+            return Thread.currentThread().getContextClassLoader().loadClass(type);
+        } catch (ClassNotFoundException e) {
+            throw new SKException(
+                "Could not load class for type: " + type + " when for input variable " + name +
+                    ", note this needs to be a fully qualified class name, i.e 'java.lang.String'.");
+        }
+    }
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/KernelFunctionFromMethod.java

@@ -16,20 +16,18 @@ import com.microsoft.semantickernel.orchestration.MethodDetails;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableType;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypeConverter;
+import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypeConverter.NoopConverter;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypes;
 import com.microsoft.semantickernel.orchestration.contextvariables.KernelArguments;
 import com.microsoft.semantickernel.plugin.KernelParameterMetadata;
 import com.microsoft.semantickernel.plugin.KernelReturnParameterMetadata;
 import com.microsoft.semantickernel.plugin.annotations.DefineKernelFunction;
 import com.microsoft.semantickernel.plugin.annotations.KernelFunctionParameter;
-
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.lang.reflect.Parameter;
 import java.util.Arrays;
-import java.util.HashSet;
 import java.util.List;
-import java.util.Set;
 import java.util.function.Function;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -49,8 +47,10 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
     private KernelFunctionFromMethod(
         ImplementationFunc implementationFunc,
         String functionName,
+        @Nullable
         String description,
-        List<KernelParameterMetadata> parameters,
+        @Nullable
+        List<KernelParameterMetadata<?>> parameters,
         KernelReturnParameterMetadata<?> returnParameter) {
         super(
             new KernelFunctionMetadata(
@@ -68,8 +68,12 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
     public <T> Mono<FunctionResult<T>> invokeAsync(
         Kernel kernel,
         @Nullable KernelArguments arguments,
-        ContextVariableType<T> variableType) {
-        return function.invoke(kernel, this, arguments, kernel.getHookService());
+        @Nullable ContextVariableType<T> variableType) {
+        return invokeAsync(
+            kernel,
+            arguments,
+            kernel.getHookService(),
+            variableType);
     }
 
     @Override
@@ -77,13 +81,41 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
         Kernel kernel,
         @Nullable KernelArguments arguments,
         @Nullable KernelHooks kernelHooks,
-        ContextVariableType<T> variableType) {
+        @Nullable ContextVariableType<T> variableType) {
 
         if (kernelHooks == null) {
             kernelHooks = kernel.getHookService();
         }
 
-        return function.invoke(kernel, this, arguments, kernelHooks);
+        return function
+            .invoke(kernel, this, arguments, kernelHooks)
+            .map(it -> convertVariableToReturnType(variableType, it));
+    }
+
+    private <T> FunctionResult convertVariableToReturnType(
+        @Nullable ContextVariableType<T> variableType,
+        FunctionResult<Object> it) {
+        if (variableType != null) {
+            return new FunctionResult<>(
+                variableType.of(it.getResult()),
+                it.getMetadata());
+        } else {
+            Object result = it.getResult();
+            if (result != null && getMetadata().getReturnParameter().getParameterType()
+                .isAssignableFrom(result.getClass())) {
+                return new FunctionResult<>(
+                    new ContextVariable<>(
+                        new ContextVariableType<>(
+                            new NoopConverter(
+                                getMetadata().getReturnParameter().getParameterType()),
+                            getMetadata().getReturnParameter().getParameterType()
+                        ),
+                        it.getResult())
+                );
+            }
+            throw new RuntimeException("Unable to convert result to type: "
+                + getMetadata().getReturnParameter().getParameterType().getName());
+        }
     }
 
     public interface ImplementationFunc {
@@ -100,9 +132,13 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
     public static KernelFunction create(
         Method method,
         Object target,
+        @Nullable
         String functionName,
+        @Nullable
         String description,
-        List<KernelParameterMetadata> parameters,
+        @Nullable
+        List<KernelParameterMetadata<?>> parameters,
+        @Nullable
         KernelReturnParameterMetadata<?> returnParameter) {
 
         MethodDetails methodDetails = getMethodDetails(functionName, method, target);
@@ -129,6 +165,7 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
 
 
     private static MethodDetails getMethodDetails(
+        @Nullable
         String functionName,
         Method method,
         Object target) {
@@ -142,12 +179,19 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
             returnDescription = annotation.returnDescription();
         }
 
+        if (functionName == null) {
+            functionName = method.getName();
+        }
+
         return new MethodDetails(
             functionName,
             description,
             getFunction(method, target),
             getParameters(method),
-            new KernelReturnParameterMetadata<>(returnDescription, method.getReturnType())
+            new KernelReturnParameterMetadata<>(
+                returnDescription,
+                method.getReturnType()
+            )
         );
     }
 
@@ -193,11 +237,30 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
                         });
 
                     return r
-                        .map(it -> new FunctionResult<>(ContextVariable.of(it)))
+                        .map(it -> {
+                            return new FunctionResult(
+                                new ContextVariable(
+                                    new ContextVariableType(
+                                        new NoopConverter(
+                                            function
+                                                .getMetadata()
+                                                .getReturnParameter()
+                                                .getParameterType()
+                                        ),
+                                        function
+                                            .getMetadata()
+                                            .getReturnParameter()
+                                            .getParameterType()
+                                    ),
+                                    it));
+                        })
                         .map(it -> {
                             FunctionInvokedEvent<T> updatedResult = kernelHooks
                                 .executeHooks(
-                                    new FunctionInvokedEvent<>(function, updatedArguments, it));
+                                    new FunctionInvokedEvent<>(
+                                        function,
+                                        updatedArguments,
+                                        it));
                             return updatedResult.getResult();
                         });
                 } catch (Exception e) {
@@ -239,6 +302,7 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
                     .subscribeOn(Schedulers.boundedElastic()));
     }
 
+    @Nullable
     private static Function<Parameter, Object> getParameters(
         Method method,
         @Nullable
@@ -253,6 +317,7 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
         };
     }
 
+    @Nullable
     private static Object getArgumentValue(
         Method method,
         @Nullable KernelArguments context,
@@ -265,15 +330,16 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
             KernelFunctionParameter annotation =
                 parameter.getAnnotation(KernelFunctionParameter.class);
             if (annotation != null) {
-                    // Convert from the defaultValue, which is a String to the argument type
-                    // Expectation here is that the fromPromptString method will be able to handle a null or empty string
-                    Class<?> type = annotation.type();
-                    ContextVariableType<?> cvType = ContextVariableTypes.getDefaultVariableTypeForClass(type);
-                    if (cvType != null) {
-                        String defaultValue = annotation.defaultValue();
-                        Object value = cvType.getConverter().fromPromptString(defaultValue);
-                        arg = ContextVariable.of(value);
-                    }
+                // Convert from the defaultValue, which is a String to the argument type
+                // Expectation here is that the fromPromptString method will be able to handle a null or empty string
+                Class<?> type = annotation.type();
+                ContextVariableType<?> cvType = ContextVariableTypes.getDefaultVariableTypeForClass(
+                    type);
+                if (cvType != null) {
+                    String defaultValue = annotation.defaultValue();
+                    Object value = cvType.getConverter().fromPromptString(defaultValue);
+                    arg = ContextVariable.untypedOf(value, cvType.getConverter());
+                }
 
                 if (arg != null && NO_DEFAULT_VALUE.equals(arg.getValue())) {
                     if (!annotation.required()) {
@@ -331,19 +397,22 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
 
         Object value = arg;
 
-        if (parameter.getType().isAssignableFrom(arg.getValue().getClass())) {
-            return arg.getValue();
-        }
+        if (arg != null) {
 
-        if (isPrimative(arg.getValue().getClass(), parameter.getType())) {
-            return arg.getValue();
-        }
+            if (parameter.getType().isAssignableFrom(arg.getType().getClazz())) {
+                return arg.getValue();
+            }
 
-        ContextVariableTypeConverter<?> c = arg.getType().getConverter();
+            if (isPrimative(arg.getType().getClazz(), parameter.getType())) {
+                return arg.getValue();
+            }
 
-        Object converted = c.toObject(arg.getValue(), parameter.getType());
-        if (converted != null) {
-            return converted;
+            ContextVariableTypeConverter<?> c = arg.getType().getConverter();
+
+            Object converted = c.toObject(arg.getValue(), parameter.getType());
+            if (converted != null) {
+                return converted;
+            }
         }
 
         // Well-known types only
@@ -366,6 +435,7 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
         return value;
     }
 
+    @SuppressWarnings("OperatorPrecedence")
     private static boolean isPrimative(Class<?> argType, Class<?> param) {
         return (argType == Byte.class || argType == byte.class) && (param == Byte.class
             || param == byte.class) ||
@@ -415,81 +485,7 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
             + " was invoked with a required context variable missing and no default value.";
     }
 
-    private static Set<Parameter> determineInputArgs(Method method) {
-        // Something is bound to the input if either:
-        // - it is annotated with @SKFunctionInputAttribute
-        // - SKFunctionParameters annotation has a name of "input"
-        // - the arg name is "input"
-        // - there is only 1 string argument to the function
-
-        // Get all parameters annotated with SKFunctionInputAttribute
-        List<Parameter> annotated =
-            Arrays.stream(method.getParameters())
-                .filter(it -> it.isAnnotationPresent(KernelFunctionParameter.class))
-                .collect(Collectors.toList());
-
-        if (annotated.size() > 1) {
-            LOGGER.warn(
-                "Multiple arguments of "
-                    + method.getName()
-                    + " have the @SKFunctionInputAttribute annotation. This is likely an"
-                    + " error.");
-        }
-
-        // Get all parameters annotated with SKFunctionParameters with a name of "input"
-        List<Parameter> annotatedWithName =
-            Arrays.stream(method.getParameters())
-                .filter(it -> it.isAnnotationPresent(KernelFunctionParameter.class))
-                .filter(it -> it.getName().equals("input"))
-                .collect(Collectors.toList());
-
-        if (annotatedWithName.size() > 1) {
-            LOGGER.warn(
-                "Multiple arguments of "
-                    + method.getName()
-                    + " have the name input. This is likely an error.");
-        }
-
-        // Get all parameters named "input", this will frequently fail as compilers strip out
-        // argument names
-        List<Parameter> calledInput =
-            Arrays.stream(method.getParameters())
-                .filter(it -> getGetVariableName(it).equals("input"))
-                .collect(Collectors.toList());
-
-        // Get parameter if there is only 1 string, and it has not been annotated with
-        // SKFunctionParameters
-        List<Parameter> soloString =
-            Arrays.stream(method.getParameters())
-                .filter(it -> it.getType().equals(String.class))
-                .filter(
-                    it ->
-                        !(it.isAnnotationPresent(KernelFunctionParameter.class)
-                            && !it.getAnnotation(KernelFunctionParameter.class)
-                            .name()
-                            .isEmpty()))
-                .collect(Collectors.toList());
-        if (soloString.size() > 1) {
-            soloString.clear();
-        }
-
-        Set<Parameter> params = new HashSet<>();
-        params.addAll(annotated);
-        params.addAll(annotatedWithName);
-        params.addAll(calledInput);
-        params.addAll(soloString);
-
-        if (params.size() > 1) {
-            LOGGER.warn(
-                "Multiple arguments of "
-                    + method.getName()
-                    + " are bound to the input variable. This is likely an error.");
-        }
-
-        return params;
-    }
-
-    private static List<KernelParameterMetadata> getParameters(Method method) {
+    private static List<KernelParameterMetadata<?>> getParameters(Method method) {
         return
             Arrays.stream(method
                     .getParameters())
@@ -497,7 +493,7 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
                 .collect(Collectors.toList());
     }
 
-    private static KernelParameterMetadata toKernelParameterMetadata(Parameter parameter) {
+    private static KernelParameterMetadata<?> toKernelParameterMetadata(Parameter parameter) {
         KernelFunctionParameter annotation = parameter.getAnnotation(
             KernelFunctionParameter.class);
 
@@ -505,19 +501,22 @@ public class KernelFunctionFromMethod extends DefaultKernelFunction {
         String description = null;
         String defaultValue = null;
         boolean isRequired = true;
+        Class<?> type = parameter.getType();
 
         if (annotation != null) {
             name = annotation.name();
             description = annotation.description();
             defaultValue = annotation.defaultValue();
             isRequired = annotation.required();
+            type = annotation.type();
         }
 
-        return new KernelParameterMetadata(
+        return new KernelParameterMetadata<>(
             name,
             description,
-            null,
-            defaultValue, isRequired
+            type,
+            defaultValue,
+            isRequired
         );
     }
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/KernelFunctionFromPrompt.java

@@ -8,6 +8,7 @@ import com.microsoft.semantickernel.Kernel;
 import com.microsoft.semantickernel.TextAIService;
 import com.microsoft.semantickernel.chatcompletion.AuthorRole;
 import com.microsoft.semantickernel.chatcompletion.ChatCompletionService;
+import com.microsoft.semantickernel.exceptions.SKException;
 import com.microsoft.semantickernel.hooks.FunctionInvokedEvent;
 import com.microsoft.semantickernel.hooks.FunctionInvokingEvent;
 import com.microsoft.semantickernel.hooks.KernelHooks;
@@ -21,6 +22,7 @@ import com.microsoft.semantickernel.orchestration.PromptExecutionSettings;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableType;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypes;
+import com.microsoft.semantickernel.orchestration.contextvariables.DefaultKernelArguments;
 import com.microsoft.semantickernel.orchestration.contextvariables.KernelArguments;
 import com.microsoft.semantickernel.services.AIServiceSelection;
 import com.microsoft.semantickernel.textcompletion.TextGenerationService;
@@ -28,6 +30,7 @@ import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.UUID;
 import javax.annotation.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -47,7 +50,7 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
         Map<String, PromptExecutionSettings> executionSettings) {
         super(
             new KernelFunctionMetadata(
-                promptConfig.getName(),
+                getName(promptConfig),
                 promptConfig.getDescription(),
                 promptConfig.getKernelParametersMetadata(),
                 promptConfig.getKernelReturnParameterMetadata()
@@ -57,6 +60,14 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
         this.template = template;
     }
 
+    private static String getName(PromptTemplateConfig promptConfig) {
+        if (promptConfig.getName() == null) {
+            return UUID.randomUUID().toString();
+        } else {
+            return promptConfig.getName();
+        }
+    }
+
     public static KernelFunction create(
         PromptTemplateConfig promptConfig
     ) {
@@ -91,10 +102,17 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
 
     private <T> Flux<FunctionResult<T>> invokeInternalAsync(
         Kernel kernel,
-        @Nullable KernelArguments arguments,
+        @Nullable KernelArguments argumentsIn,
         KernelHooks kernelHooks,
         ContextVariableType<T> variableType) {
 
+        KernelArguments arguments;
+        if (argumentsIn == null) {
+            arguments = new DefaultKernelArguments();
+        } else {
+            arguments = argumentsIn;
+        }
+
         PromptRenderingEvent preRenderingHookResult = kernelHooks
             .executeHooks(new PromptRenderingEvent(this, arguments));
 
@@ -121,6 +139,11 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
                         args
                     );
 
+                if (aiServiceSelection == null) {
+                    throw new IllegalStateException(
+                        "Failed to initialise aiService, could not find any TextAIService implementations");
+                }
+
                 AIService client = aiServiceSelection.getService();
                 if (client == null) {
                     throw new IllegalStateException(
@@ -162,8 +185,13 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
                                 );
                             } else if (chatMessageContent.getAuthorRole()
                                 == AuthorRole.TOOL) {
+                                String content = chatMessageContent.getContent();
+                                if (content == null || content.isEmpty()) {
+                                    return Flux.error(new IllegalStateException(
+                                        "Tool message content is empty"));
+                                }
                                 Mono<FunctionResult<String>> toolResult = invokeTool(kernel,
-                                    chatMessageContent.getContent());
+                                    content);
                                 return toolResult.flux();
                             }
                             return Flux.empty();
@@ -238,8 +266,8 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
                     if (ex instanceof HttpResponseException
                         && ((HttpResponseException) ex).getResponse().getStatusCode()
                         == 400
-                        && ex.getMessage()
-                        .contains("parameters are not available" + " on")) {
+                        && ex.getMessage() != null
+                        && ex.getMessage().contains("parameters are not available" + " on")) {
                         LOGGER.warn(
                             "This error indicates that you have attempted"
                                 + " to use a chat completion model in a"
@@ -258,7 +286,13 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
         Kernel kernel,
         @Nullable KernelArguments arguments,
         @Nullable KernelHooks kernelHooks,
+        @Nullable
         ContextVariableType<T> variableType) {
+        if (variableType == null) {
+            return Mono.error(new SKException(
+                "Cannot invoke a prompt function without a variable return type. Ensure that there is"
+                    + " a valid type converter for the return type of the prompt function."));
+        }
         if (kernelHooks == null) {
             kernelHooks = kernel.getHookService();
         }
@@ -270,7 +304,9 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
     @Override
     public <T> Mono<FunctionResult<T>> invokeAsync(
         Kernel kernel,
-        @Nullable KernelArguments arguments,
+        @Nullable
+        KernelArguments arguments,
+        @Nullable
         ContextVariableType<T> variableType) {
         return invokeAsync(kernel, arguments, null, variableType);
     }
@@ -300,6 +336,7 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
     /*
      * The jsonNode should represent: {"name":"search-search", "parameters": {"query":"Banksy"}}}
      */
+    @SuppressWarnings("StringSplitter")
     private Mono<FunctionResult<String>> invokeFunction(Kernel kernel, JsonNode jsonNode) {
         String name = jsonNode.get("name").asText();
         String[] parts = name.split("-");
@@ -307,22 +344,25 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
         String fnName = parts.length > 1 ? parts[1] : "";
         JsonNode parameters = jsonNode.get("parameters");
         if (parameters != null) {
-            KernelFunction kernelFunction = kernel.getPlugins().getFunction(pluginName, fnName);
-            if (kernelFunction == null) {
-                return Mono.empty();
+            try {
+                KernelFunction kernelFunction = kernel.getPlugins().getFunction(pluginName, fnName);
+
+                ContextVariableType<String> variableType = ContextVariableTypes.getDefaultVariableTypeForClass(
+                    String.class);
+                Map<String, ContextVariable<?>> variables = new HashMap<>();
+                parameters.fields().forEachRemaining(entry -> {
+                    String paramName = entry.getKey();
+                    String paramValue = entry.getValue().asText();
+                    ContextVariable<String> contextVariable = new ContextVariable<>(variableType,
+                        paramValue);
+                    variables.put(paramName, contextVariable);
+                });
+                KernelArguments arguments = KernelArguments.builder().withVariables(variables)
+                    .build();
+                return kernelFunction.invokeAsync(kernel, arguments, variableType);
+            } catch (Exception e) {
+                return Mono.error(e);
             }
-            ContextVariableType<String> variableType = ContextVariableTypes.getDefaultVariableTypeForClass(
-                String.class);
-            Map<String, ContextVariable<?>> variables = new HashMap<>();
-            parameters.fields().forEachRemaining(entry -> {
-                String paramName = entry.getKey();
-                String paramValue = entry.getValue().asText();
-                ContextVariable<String> contextVariable = new ContextVariable<>(variableType,
-                    paramValue);
-                variables.put(paramName, contextVariable);
-            });
-            KernelArguments arguments = KernelArguments.builder().withVariables(variables).build();
-            return kernelFunction.invokeAsync(kernel, arguments, variableType);
         }
         return Mono.empty();
     }
@@ -351,6 +391,14 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
         @Nullable String templateFormat,
         @Nullable PromptTemplateFactory promptTemplateFactory) {
 
+        if (templateFormat == null) {
+            templateFormat = PromptTemplateConfig.SEMANTIC_KERNEL_TEMPLATE_FORMAT;
+        }
+
+        if (functionName == null) {
+            functionName = UUID.randomUUID().toString();
+        }
+
         return new KernelFunctionFromPrompt.Builder()
             .withName(functionName)
             .withDescription(description)
@@ -367,37 +415,50 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
 
     public static final class Builder implements FromPromptBuilder {
 
+        @Nullable
         private PromptTemplate promptTemplate;
+        @Nullable
         private String name;
-        private Map<String, PromptExecutionSettings> executionSettings;
+        @Nullable
+        private Map<String, PromptExecutionSettings> executionSettings = null;
+        @Nullable
         private String description;
+        @Nullable
         private List<InputVariable> inputVariables;
+        @Nullable
         private String template;
         private String templateFormat = PromptTemplateConfig.SEMANTIC_KERNEL_TEMPLATE_FORMAT;
+        @Nullable
         private OutputVariable outputVariable;
+        @Nullable
         private PromptTemplateFactory promptTemplateFactory;
 
 
         @Override
-        public FromPromptBuilder withName(String name) {
+        public FromPromptBuilder withName(@Nullable String name) {
             this.name = name;
             return this;
         }
 
         @Override
-        public FromPromptBuilder withInputParameters(List<InputVariable> inputVariables) {
-            this.inputVariables = new ArrayList<>(inputVariables);
+        public FromPromptBuilder withInputParameters(@Nullable List<InputVariable> inputVariables) {
+            if (inputVariables != null) {
+                this.inputVariables = new ArrayList<>(inputVariables);
+            } else {
+                this.inputVariables = null;
+            }
             return this;
         }
 
         @Override
-        public FromPromptBuilder withPromptTemplate(PromptTemplate promptTemplate) {
+        public FromPromptBuilder withPromptTemplate(@Nullable PromptTemplate promptTemplate) {
             this.promptTemplate = promptTemplate;
             return this;
         }
 
         @Override
         public FromPromptBuilder withExecutionSettings(
+            @Nullable
             Map<String, PromptExecutionSettings> executionSettings) {
             if (this.executionSettings == null) {
                 this.executionSettings = new HashMap<>();
@@ -411,7 +472,11 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
 
         @Override
         public FromPromptBuilder withDefaultExecutionSettings(
-            PromptExecutionSettings executionSettings) {
+            @Nullable PromptExecutionSettings executionSettings) {
+            if (executionSettings == null) {
+                return this;
+            }
+
             if (this.executionSettings == null) {
                 this.executionSettings = new HashMap<>();
             }
@@ -426,13 +491,13 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
         }
 
         @Override
-        public FromPromptBuilder withDescription(String description) {
+        public FromPromptBuilder withDescription(@Nullable String description) {
             this.description = description;
             return this;
         }
 
         @Override
-        public FromPromptBuilder withTemplate(String template) {
+        public FromPromptBuilder withTemplate(@Nullable String template) {
             this.template = template;
             return this;
         }
@@ -445,13 +510,14 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
         }
 
         @Override
-        public FromPromptBuilder withOutputVariable(OutputVariable outputVariable) {
+        public FromPromptBuilder withOutputVariable(@Nullable OutputVariable outputVariable) {
             this.outputVariable = outputVariable;
             return this;
         }
 
         @Override
         public FromPromptBuilder withPromptTemplateFactory(
+            @Nullable
             PromptTemplateFactory promptTemplateFactory) {
             this.promptTemplateFactory = promptTemplateFactory;
             return this;
@@ -459,6 +525,11 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
 
         @Override
         public KernelFunction build() {
+
+            if (template == null) {
+                throw new IllegalStateException("Template must be provided");
+            }
+
             PromptTemplateConfig config = new PromptTemplateConfig(
                 name,
                 template,
@@ -483,6 +554,11 @@ public class KernelFunctionFromPrompt extends DefaultKernelFunction {
         }
 
         public KernelFunction build(PromptTemplateConfig functionModel) {
+
+            if (promptTemplate == null) {
+                throw new IllegalStateException("Template must be provided");
+            }
+
             return new KernelFunctionFromPrompt(
                 promptTemplate,
                 functionModel,

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/KernelPromptTemplateFactory.java

@@ -5,11 +5,12 @@ import static com.microsoft.semantickernel.semanticfunctions.PromptTemplateConfi
 
 import com.microsoft.semantickernel.templateengine.handlebars.HandlebarsPromptTemplate;
 import com.microsoft.semantickernel.templateengine.semantickernel.DefaultPromptTemplate;
-import javax.annotation.Nonnull;
 import java.util.Locale;
+import javax.annotation.Nonnull;
 
 public class KernelPromptTemplateFactory implements PromptTemplateFactory {
 
+    @Override
     public PromptTemplate tryCreate(@Nonnull PromptTemplateConfig templateConfig) {
         switch (templateConfig.getTemplateFormat().toLowerCase(Locale.ROOT)) {
             case SEMANTIC_KERNEL_TEMPLATE_FORMAT:

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/PromptTemplateConfig.java

@@ -23,18 +23,15 @@ public class PromptTemplateConfig {
 
     public static final int CURRENT_SCHEMA = 1;
     public static final String DEFAULT_CONFIG_NAME = "default";
+    @Nullable
     private String name;
-
     private String template;
-
     private String templateFormat;
-
+    @Nullable
     private String description;
-
     private List<InputVariable> inputVariables;
-
+    @Nullable
     private OutputVariable outputVariable;
-
     private Map<String, PromptExecutionSettings> executionSettings;
 
     public static final String SEMANTIC_KERNEL_TEMPLATE_FORMAT = "semantic-kernel";
@@ -56,6 +53,7 @@ public class PromptTemplateConfig {
     public PromptTemplateConfig(
         @JsonProperty("schema")
         int schema,
+        @Nullable
         @JsonProperty("name")
         String name,
         @JsonProperty("template")
@@ -65,12 +63,16 @@ public class PromptTemplateConfig {
             value = "template_format",
             defaultValue = SEMANTIC_KERNEL_TEMPLATE_FORMAT)
         String templateFormat,
+        @Nullable
         @JsonProperty("description")
         String description,
+        @Nullable
         @JsonProperty("input_variables")
         List<InputVariable> inputVariables,
+        @Nullable
         @JsonProperty("output_variable")
         OutputVariable outputVariable,
+        @Nullable
         @JsonProperty("execution_settings")
         Map<String, PromptExecutionSettings> executionSettings) {
         this.name = name;
@@ -104,8 +106,19 @@ public class PromptTemplateConfig {
      * @param outputVariable    Output variable
      * @param executionSettings Execution settings
      */
-    public PromptTemplateConfig(String name, String template, String templateFormat,
-        String description, List<InputVariable> inputVariables, OutputVariable outputVariable,
+    public PromptTemplateConfig(
+        @Nullable
+        String name,
+        String template,
+        @Nullable
+        String templateFormat,
+        @Nullable
+        String description,
+        @Nullable
+        List<InputVariable> inputVariables,
+        @Nullable
+        OutputVariable outputVariable,
+        @Nullable
         Map<String, PromptExecutionSettings> executionSettings) {
         this(
             CURRENT_SCHEMA,
@@ -131,16 +144,16 @@ public class PromptTemplateConfig {
         );
     }
 
-    public List<KernelParameterMetadata> getKernelParametersMetadata() {
+    public List<KernelParameterMetadata<?>> getKernelParametersMetadata() {
         if (inputVariables == null) {
             return Collections.emptyList();
         }
         return inputVariables
             .stream()
-            .map(inputVariable -> new KernelParameterMetadata(
+            .map(inputVariable -> new KernelParameterMetadata<>(
                 inputVariable.getName(),
                 inputVariable.getDescription(),
-                null,
+                inputVariable.getTypeClass(),
                 inputVariable.getDefaultValue(), inputVariable.isRequired()
             ))
             .collect(Collectors.toList());
@@ -161,6 +174,7 @@ public class PromptTemplateConfig {
         inputVariables.add(inputVariable);
     }
 
+    @Nullable
     public String getName() {
         return name;
     }
@@ -186,6 +200,7 @@ public class PromptTemplateConfig {
         this.templateFormat = templateFormat;
     }
 
+    @Nullable
     public String getDescription() {
         return description;
     }
@@ -202,6 +217,7 @@ public class PromptTemplateConfig {
         this.inputVariables = new ArrayList<>(inputVariables);
     }
 
+    @Nullable
     public OutputVariable getOutputVariable() {
         return outputVariable;
     }
@@ -210,8 +226,12 @@ public class PromptTemplateConfig {
         this.outputVariable = outputVariable;
     }
 
+    @Nullable
     public Map<String, PromptExecutionSettings> getExecutionSettings() {
-        return Collections.unmodifiableMap(executionSettings);
+        if (executionSettings != null) {
+            return Collections.unmodifiableMap(executionSettings);
+        }
+        return null;
     }
 
 

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/semanticfunctions/PromptTemplateFactory.java

@@ -1,5 +1,7 @@
 package com.microsoft.semantickernel.semanticfunctions;
 
+import javax.annotation.Nullable;
+
 public interface PromptTemplateFactory {
 
     PromptTemplate tryCreate(PromptTemplateConfig templateConfig);
@@ -10,7 +12,7 @@ public interface PromptTemplateFactory {
 
     class UnknownTemplateFormatException extends IllegalArgumentException {
 
-        public UnknownTemplateFormatException(String templateFormat) {
+        public UnknownTemplateFormatException(@Nullable String templateFormat) {
             super("Unknown template format: " + templateFormat);
         }
     }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/services/AIServiceSelection.java

@@ -3,6 +3,7 @@ package com.microsoft.semantickernel.services;
 
 import com.microsoft.semantickernel.AIService;
 import com.microsoft.semantickernel.orchestration.PromptExecutionSettings;
+import javax.annotation.Nullable;
 
 /**
  * The result of an AI service selection.
@@ -10,6 +11,7 @@ import com.microsoft.semantickernel.orchestration.PromptExecutionSettings;
 public class AIServiceSelection<T extends AIService> {
 
     private final T service;
+    @Nullable
     private final PromptExecutionSettings settings;
 
     /**
@@ -19,7 +21,7 @@ public class AIServiceSelection<T extends AIService> {
      * @param settings The settings associated with the selected service. This may be null even if a
      *                 service is selected..
      */
-    public AIServiceSelection(T service, PromptExecutionSettings settings) {
+    public AIServiceSelection(T service, @Nullable PromptExecutionSettings settings) {
         this.service = service;
         this.settings = settings;
     }
@@ -39,6 +41,7 @@ public class AIServiceSelection<T extends AIService> {
      * @return The settings associated with the selected service. This may be null even if a service
      * is selected.
      */
+    @Nullable
     public PromptExecutionSettings getSettings() {
         return settings;
     }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/services/OrderedAIServiceSelector.java

@@ -29,6 +29,7 @@ public class OrderedAIServiceSelector extends BaseAIServiceSelector {
     }
 
     @Nullable
+    @Override
     public <T extends AIService> AIServiceSelection<T> trySelectAIService(
         Class<T> serviceType,
         @Nullable
@@ -38,9 +39,7 @@ public class OrderedAIServiceSelector extends BaseAIServiceSelector {
         Map<Class<? extends AIService>, AIService> services) {
 
         // Allow the execution settings from the kernel arguments to take precedence
-        Map<String, PromptExecutionSettings> executionSettings = null;
-
-        executionSettings = settingsFromArguments(arguments, executionSettings);
+        Map<String, PromptExecutionSettings> executionSettings = settingsFromArguments(arguments);
         executionSettings = settingsFromFunctionSettings(function, executionSettings);
 
         if (executionSettings == null || executionSettings.isEmpty()) {
@@ -105,12 +104,14 @@ public class OrderedAIServiceSelector extends BaseAIServiceSelector {
         }
 
         AIService service = getAnyService(serviceType);
-        PromptExecutionSettings settings;
+        PromptExecutionSettings settings = null;
 
-        if (executionSettings.containsKey(PromptExecutionSettings.DEFAULT_SERVICE_ID)) {
-            settings = executionSettings.get(PromptExecutionSettings.DEFAULT_SERVICE_ID);
-        } else {
-            settings = executionSettings.values().stream().findFirst().orElseGet(() -> null);
+        if (executionSettings != null && !executionSettings.isEmpty()) {
+            if (executionSettings.containsKey(PromptExecutionSettings.DEFAULT_SERVICE_ID)) {
+                settings = executionSettings.get(PromptExecutionSettings.DEFAULT_SERVICE_ID);
+            } else {
+                settings = executionSettings.values().stream().findFirst().orElseGet(() -> null);
+            }
         }
 
         if (service != null) {
@@ -125,6 +126,7 @@ public class OrderedAIServiceSelector extends BaseAIServiceSelector {
     private static Map<String, PromptExecutionSettings> settingsFromFunctionSettings(
         @Nullable
         KernelFunction function,
+        @Nullable
         Map<String, PromptExecutionSettings> executionSettings) {
         if (executionSettings == null || executionSettings.isEmpty()) {
             if (function != null) {
@@ -136,12 +138,12 @@ public class OrderedAIServiceSelector extends BaseAIServiceSelector {
 
     @Nullable
     private static Map<String, PromptExecutionSettings> settingsFromArguments(
-        @Nullable KernelArguments arguments,
-        Map<String, PromptExecutionSettings> executionSettings) {
+        @Nullable
+        KernelArguments arguments) {
         if (arguments != null) {
-            executionSettings = arguments.getExecutionSettings();
+            return arguments.getExecutionSettings();
         }
-        return executionSettings;
+        return null;
     }
 
     private AIService getServiceByModelId(String modelId) {
@@ -189,6 +191,7 @@ public class OrderedAIServiceSelector extends BaseAIServiceSelector {
         return service;
     }
 
+    @Nullable
     AIService getAnyService(Class<? extends AIService> serviceType) {
         List<AIService> services = getServices(serviceType);
         if (services.isEmpty()) {

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/templateengine/handlebars/HandlebarsPromptTemplate.java

@@ -10,6 +10,7 @@ import com.microsoft.semantickernel.chatcompletion.ChatHistory;
 import com.microsoft.semantickernel.chatcompletion.ChatMessageContent;
 import com.microsoft.semantickernel.orchestration.KernelFunction;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
+import com.microsoft.semantickernel.orchestration.contextvariables.DefaultKernelArguments;
 import com.microsoft.semantickernel.orchestration.contextvariables.KernelArguments;
 import com.microsoft.semantickernel.plugin.KernelParameterMetadata;
 import com.microsoft.semantickernel.plugin.KernelPlugin;
@@ -42,22 +43,27 @@ public class HandlebarsPromptTemplate implements PromptTemplate {
 
 
     @Override
-    public Mono<String> renderAsync(Kernel kernel,
+    public Mono<String> renderAsync(
+        Kernel kernel,
         @Nullable KernelArguments arguments) {
         HandleBarsPromptTemplateHandler handler =
             new HandleBarsPromptTemplateHandler(kernel, promptTemplate.getTemplate());
 
+        if (arguments == null) {
+            arguments = new DefaultKernelArguments();
+        }
         return handler.render(arguments);
     }
 
     private static class MessageResolver implements ValueResolver {
 
         @Override
+        @SuppressWarnings("NullAway")
         public Object resolve(Object context, String name) {
             if (context instanceof ChatMessageContent) {
-                if ("role".equals(name.toLowerCase())) {
+                if ("role".equalsIgnoreCase(name)) {
                     return ((ChatMessageContent) context).getAuthorRole().name();
-                } else if ("content".equals(name.toLowerCase())) {
+                } else if ("content".equalsIgnoreCase(name)) {
                     return ((ChatMessageContent) context).getContent();
                 }
             }
@@ -67,7 +73,8 @@ public class HandlebarsPromptTemplate implements PromptTemplate {
         @Override
         public Object resolve(Object context) {
             if (context instanceof ChatMessageContent) {
-                return ((ChatMessageContent) context).getContent();
+                String result = ((ChatMessageContent) context).getContent();
+                return result != null ? result : UNRESOLVED;
             }
             return UNRESOLVED;
         }
@@ -93,9 +100,9 @@ public class HandlebarsPromptTemplate implements PromptTemplate {
             }
             if (context instanceof KernelFunction) {
                 KernelFunction function = (KernelFunction) context;
-                if ("pluginname".equals(name.toLowerCase())) {
+                if ("pluginname".equalsIgnoreCase(name)) {
                     return function.getSkillName();
-                } else if ("name".equals(name.toLowerCase())) {
+                } else if ("name".equalsIgnoreCase(name)) {
                     return function.getName();
                 }
             }
@@ -120,19 +127,26 @@ public class HandlebarsPromptTemplate implements PromptTemplate {
 
         @Override
         public Object resolve(Object context, String name) {
+            Object value = null;
             if (context instanceof KernelArguments) {
-                return ((KernelArguments) context).get(name).getValue();
+                ContextVariable<?> variable = ((KernelArguments) context).get(name);
+                value = variable != null ? variable.getValue() : null;
             }
             if (context instanceof ContextVariable) {
-                return ((ContextVariable<?>) context).getValue();
+                value = ((ContextVariable<?>) context).getValue();
+            }
+            if (value == null) {
+                return UNRESOLVED;
+            } else {
+                return value;
             }
-            return UNRESOLVED;
         }
 
         @Override
         public Object resolve(Object context) {
             if (context instanceof ContextVariable) {
-                return ((ContextVariable<?>) context).getValue();
+                Object result = ((ContextVariable<?>) context).getValue();
+                return result != null ? result : UNRESOLVED;
             }
             return UNRESOLVED;
         }
@@ -182,7 +196,7 @@ public class HandlebarsPromptTemplate implements PromptTemplate {
                 String.format(
                     "<function pluginName=\"%s\" name=\"%s\" description=\"%s\">",
                     pluginName, functionName, description));
-            List<KernelParameterMetadata> parameters = function.getMetadata().getParameters();
+            List<KernelParameterMetadata<?>> parameters = function.getMetadata().getParameters();
             parameters.forEach(p -> {
                 sb.append(String.format(
                     "<parameter name=\"%s\" description=\"%s\" defaultValue=\"%s\" isRequired=\"%s\" type=\"%s\"/>",

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/templateengine/semantickernel/CodeTokenizer.java

@@ -116,7 +116,7 @@ public class CodeTokenizer {
         for (int nextCharCursor = 1; nextCharCursor < text.length(); nextCharCursor++) {
             char currentChar = nextChar;
             nextChar = text.charAt(nextCharCursor);
-            
+
             if (skipNextChar) {
                 skipNextChar = false;
                 continue;
@@ -161,7 +161,7 @@ public class CodeTokenizer {
                     spaceSeparatorFound = false;
                 } else if (currentChar == namedArgValuePrefix
                     && currentTokenType == TokenTypes.NamedArg) {
-                    blocks.add(new NamedArgBlock(currentTokenContent.toString()));
+                    blocks.add(NamedArgBlock.from(currentTokenContent.toString()));
                     currentTokenContent = new StringBuilder();
                     currentTokenType = TokenTypes.None;
                     spaceSeparatorFound = false;
@@ -195,7 +195,7 @@ public class CodeTokenizer {
                 } else if (currentTokenType == TokenTypes.NamedArg && namedArgSeparatorFound
                     && namedArgValuePrefix != 0) {
                     blocks.add(
-                        new NamedArgBlock(currentTokenContent.toString()));
+                        NamedArgBlock.from(currentTokenContent.toString()));
                     currentTokenContent = new StringBuilder();
                     namedArgSeparatorFound = false;
                     namedArgValuePrefix = '\0';
@@ -277,7 +277,7 @@ public class CodeTokenizer {
 
                 break;
             case NamedArg:
-                blocks.add(new NamedArgBlock(currentTokenContent.toString()));
+                blocks.add(NamedArgBlock.from(currentTokenContent.toString()));
                 break;
 
             case None:
@@ -305,6 +305,7 @@ public class CodeTokenizer {
         return c == Symbols.DblQuote || c == Symbols.SglQuote || c == Symbols.EscapeChar;
     }
 
+    @SuppressWarnings("NullAway")
     @Nullable
     private static NamedArgBlock getNamedArg(String tokenContent) {
 
@@ -314,7 +315,6 @@ public class CodeTokenizer {
         if (Verify.isNullOrEmpty(name) || Verify.isNullOrEmpty(value)) {
             return null;
         }
-
         NamedArgBlock block = new NamedArgBlock(tokenContent, name, value);
         if (block.isValid()) {
             return block;

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/templateengine/semantickernel/DefaultPromptTemplate.java

@@ -63,10 +63,8 @@ public class DefaultPromptTemplate implements PromptTemplate {
     /// Augments <paramref name="config"/>'s <see cref="PromptTemplateConfig.InputVariables"/> with any variables
     /// not already contained there but that are referenced in the prompt template.
     /// </summary>
+    @SuppressWarnings("NullAway")
     private void addMissingInputVariables(List<Block> blocks) {
-        if (promptTemplate == null) {
-            return;
-        }
         // Add all of the existing input variables to our known set. We'll avoid adding any
         // dynamically discovered input variables with the same name.
         Set<String> seen = new HashSet<>();
@@ -84,7 +82,8 @@ public class DefaultPromptTemplate implements PromptTemplate {
             if (block.getType() == BlockTypes.Variable) {
                 name = ((VarBlock) block).getName();
             } else if (block.getType() == BlockTypes.NamedArg) {
-                name = ((NamedArgBlock) block).getVarBlock().getName();
+                VarBlock blockName = ((NamedArgBlock) block).getVarBlock();
+                name = blockName == null ? null : blockName.getName();
             }
 
             if (!Verify.isNullOrEmpty(name) && !seen.contains(name)) {

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/templateengine/semantickernel/TemplateException.java

@@ -7,10 +7,12 @@ import javax.annotation.Nullable;
 
 public class TemplateException extends SKException {
 
-    @Nonnull private final ErrorCodes errorCode;
+    @Nonnull
+    private final ErrorCodes errorCode;
 
     /**
-     * Initializes a new instance of the {@code TemplateException} class with a provided error code.
+     * Initializes a new instance of the {@code TemplateException} class with a provided error
+     * code.
      *
      * @param error The error code.
      */
@@ -19,26 +21,28 @@ public class TemplateException extends SKException {
     }
 
     /**
-     * Initializes a new instance of the {@code TemplateException} class with a provided error code.
+     * Initializes a new instance of the {@code TemplateException} class with a provided error
+     * code.
      *
      * @param errorCode The error code.
-     * @param message The exception message.
+     * @param message   The exception message.
      */
     public TemplateException(@Nonnull ErrorCodes errorCode, @Nullable String message) {
         this(errorCode, message, null);
     }
 
     /**
-     * Initializes a new instance of the {@code TemplateException} class with a provided error code.
+     * Initializes a new instance of the {@code TemplateException} class with a provided error
+     * code.
      *
-     * @param errorCode The error code.
-     * @param message The exception message.
+     * @param errorCode      The error code.
+     * @param message        The exception message.
      * @param innerException The exception that is the cause of the current exception.
      */
     public TemplateException(
-            @Nonnull ErrorCodes errorCode,
-            @Nullable String message,
-            @Nullable Throwable innerException) {
+        @Nonnull ErrorCodes errorCode,
+        @Nullable String message,
+        @Nullable Throwable innerException) {
         super(formatDefaultMessage(errorCode.getMessage(), message), innerException);
         this.errorCode = errorCode;
     }
@@ -57,19 +61,6 @@ public class TemplateException extends SKException {
 
     // spotless:off
 
-    /**
-     * <p>
-     * Translate the error code into a default message.
-     * </p>
-     */
-    //spotless:on
-    private static String getDefaultMessage(
-            @Nonnull ErrorCodes errorCode, @Nullable String message) {
-        return String.format("%s: %s", errorCode.getMessage(), message);
-    }
-
-    // spotless:off
-
     /**
      * <p>
      * Error codes for {@code TemplateException}.

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/templateengine/semantickernel/blocks/Block.java

@@ -1,8 +1,13 @@
 // Copyright (c) Microsoft. All rights reserved.
 package com.microsoft.semantickernel.templateengine.semantickernel.blocks;
 
-/** Base class for blocks parsed from a prompt template */
+import javax.annotation.Nullable;
+
+/**
+ * Base class for blocks parsed from a prompt template
+ */
 public abstract class Block {
+
     private final String content;
     private final BlockTypes type;
 
@@ -10,9 +15,11 @@ public abstract class Block {
      * Base constructor
      *
      * @param content Block content
-     * @param type Block type
+     * @param type    Block type
      */
-    public Block(String content, BlockTypes type) {
+    public Block(
+        @Nullable String content,
+        BlockTypes type) {
         if (content == null) {
             content = "";
         }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/templateengine/semantickernel/blocks/CodeBlock.java

@@ -3,19 +3,18 @@ package com.microsoft.semantickernel.templateengine.semantickernel.blocks;
 
 import com.microsoft.semantickernel.Kernel;
 import com.microsoft.semantickernel.exceptions.SKException;
+import com.microsoft.semantickernel.orchestration.FunctionResult;
 import com.microsoft.semantickernel.orchestration.KernelFunctionMetadata;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableType;
 import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariableTypes;
 import com.microsoft.semantickernel.orchestration.contextvariables.DefaultKernelArguments;
-import com.microsoft.semantickernel.orchestration.FunctionResult;
 import com.microsoft.semantickernel.orchestration.contextvariables.KernelArguments;
 import com.microsoft.semantickernel.templateengine.semantickernel.TemplateException;
-import java.util.ArrayList;
+import com.microsoft.semantickernel.templateengine.semantickernel.TemplateException.ErrorCodes;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
-import java.util.Locale;
 import java.util.Optional;
 import javax.annotation.Nullable;
 import org.slf4j.Logger;
@@ -81,7 +80,7 @@ public final class CodeBlock extends Block implements CodeRendering {
     @Override
     public Mono<String> renderCodeAsync(Kernel kernel, @Nullable KernelArguments arguments) {
         if (!this.isValid()) {
-            throw new TemplateException(TemplateException.ErrorCodes.SYNTAX_ERROR);
+            throw new TemplateException(ErrorCodes.SYNTAX_ERROR);
         }
 
         // this.Log.LogTrace("Rendering code: `{0}`", this.Content);
@@ -149,7 +148,9 @@ public final class CodeBlock extends Block implements CodeRendering {
     /// <param name="arguments">The prompt rendering arguments.</param>
     /// <returns>The function arguments.</returns>
     /// <exception cref="KernelException">Occurs when any argument other than the first is not a named argument.</exception>
-    private KernelArguments enrichFunctionArguments(Kernel kernel, FunctionIdBlock fBlock,
+    private KernelArguments enrichFunctionArguments(
+        Kernel kernel,
+        FunctionIdBlock fBlock,
         KernelArguments arguments) {
         Block firstArg = this.tokens.get(1);
 
@@ -158,14 +159,14 @@ public final class CodeBlock extends Block implements CodeRendering {
             .getFunction(fBlock.getPluginName(), fBlock.getFunctionName()).getMetadata();
 
         // Check if the function has parameters to be set
-        if (functionMetadata.getParameters().size() == 0) {
+        if (functionMetadata.getParameters().isEmpty()) {
             throw new IllegalArgumentException(
                 "Function " + fBlock.getPluginName() + "." + fBlock.getFunctionName()
                     + " does not take any arguments but it is being called in the template with {this._tokens.Count - 1} arguments.");
         }
 
         String firstPositionalParameterName = null;
-        Object firstPositionalInputValue = null;
+        Object firstPositionalInputValue;
         int namedArgsStartIndex = 1;
 
         if (firstArg.getType() != BlockTypes.NamedArg) {
@@ -175,6 +176,12 @@ public final class CodeBlock extends Block implements CodeRendering {
             firstPositionalInputValue = ((TextRendering) tokens.get(1)).render(arguments);
             // Type check is avoided and marshalling is done by the function itself
 
+            if (firstPositionalInputValue == null) {
+                throw new SKException(
+                    "Unexpected null value for first positional argument: " + tokens.get(1)
+                        .getContent());
+            }
+
             // Keep previous trust information when updating the input
             arguments.put(firstPositionalParameterName,
                 ContextVariable.of(firstPositionalInputValue));
@@ -191,8 +198,7 @@ public final class CodeBlock extends Block implements CodeRendering {
 
             // Check if the positional parameter clashes with a named parameter
             if (firstPositionalParameterName != null &&
-                firstPositionalParameterName.toLowerCase(Locale.ROOT)
-                    .equals(arg.getName().toLowerCase(Locale.ROOT))) {
+                firstPositionalParameterName.equalsIgnoreCase(arg.getName())) {
                 throw new SKException(
                     "Ambiguity found as a named parameter '{arg.Name}' cannot be set for the first parameter when there is also a positional value: '{firstPositionalInputValue}' provided. Function: {fBlock.PluginName}.{fBlock.FunctionName}");
             }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/templateengine/semantickernel/blocks/FunctionIdBlock.java

@@ -31,7 +31,7 @@ public final class FunctionIdBlock extends Block implements TextRendering {
 
     @Override
     @Nullable
-    public String render(KernelArguments variables) {
+    public String render(@Nullable KernelArguments variables) {
         return this.getContent();
     }
 

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/templateengine/semantickernel/blocks/NamedArgBlock.java

@@ -12,10 +12,14 @@ public class NamedArgBlock extends Block implements TextRendering {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(NamedArgBlock.class);
 
+    @Nullable
     private final String name;
+    @Nullable
     private final String value;
     private final VarBlock argNameAsVarBlock;
+    @Nullable
     private final VarBlock varBlock;
+    @Nullable
     private final ValBlock valBlock;
 
     public NamedArgBlock(String content, String name, String value) {
@@ -34,20 +38,47 @@ public class NamedArgBlock extends Block implements TextRendering {
         }
     }
 
-    public NamedArgBlock(String content) {
+    protected NamedArgBlock(
+        String content,
+        @Nullable
+        String name,
+        @Nullable
+        String value,
+        VarBlock argNameAsVarBlock,
+        @Nullable
+        VarBlock varBlock,
+        @Nullable
+        ValBlock valBlock) {
         super(content, NamedArg);
+        this.name = name;
+        this.value = value;
+        this.argNameAsVarBlock = argNameAsVarBlock;
+        this.varBlock = varBlock;
+        this.valBlock = valBlock;
+    }
 
-        this.name = tryGetName(content);
-        this.value = tryGetValue(content);
-        this.argNameAsVarBlock = new VarBlock(Symbols.VarPrefix + name);
+    public static NamedArgBlock from(String content) {
+
+        String name = tryGetName(content);
+        String value = tryGetValue(content);
+        VarBlock argNameAsVarBlock = new VarBlock(Symbols.VarPrefix + name);
+
+        if (value == null) {
+            throw new IllegalArgumentException("Unable to extract value from: " + content);
+        }
+
+        VarBlock varBlock;
+        ValBlock valBlock;
 
         if (value.startsWith(String.valueOf(Symbols.VarPrefix))) {
-            this.varBlock = new VarBlock(value);
+            varBlock = new VarBlock(value);
             valBlock = null;
         } else {
-            this.valBlock = new ValBlock(value);
+            valBlock = new ValBlock(value);
             varBlock = null;
         }
+
+        return new NamedArgBlock(content, name, value, argNameAsVarBlock, varBlock, valBlock);
     }
 
     @Override
@@ -72,9 +103,8 @@ public class NamedArgBlock extends Block implements TextRendering {
         return this.argNameAsVarBlock.isValid();
     }
 
-    @Nullable
     @Override
-    public String render(KernelArguments variables) {
+    public String render(@Nullable KernelArguments variables) {
         return getContent();
     }
 
@@ -84,10 +114,12 @@ public class NamedArgBlock extends Block implements TextRendering {
 
     }
 
+    @Nullable
     public String getName() {
         return name;
     }
 
+    @SuppressWarnings("NullAway")
     public String getValue(KernelArguments arguments) {
         boolean valueIsValidValBlock = this.valBlock != null && this.valBlock.isValid();
         if (valueIsValidValBlock) {
@@ -120,6 +152,7 @@ public class NamedArgBlock extends Block implements TextRendering {
         return splitAndGetPart(text, 1);
     }
 
+    @SuppressWarnings("StringSplitter")
     @Nullable
     private static String splitAndGetPart(String text, int x) {
         if (Verify.isNullOrEmpty(text)) {

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/templateengine/semantickernel/blocks/TextBlock.java

@@ -2,6 +2,7 @@
 package com.microsoft.semantickernel.templateengine.semantickernel.blocks;
 
 import com.microsoft.semantickernel.orchestration.contextvariables.KernelArguments;
+import javax.annotation.Nullable;
 
 public final class TextBlock extends Block implements TextRendering {
 
@@ -15,7 +16,7 @@ public final class TextBlock extends Block implements TextRendering {
     }
 
     @Override
-    public String render(KernelArguments variables) {
+    public String render(@Nullable KernelArguments variables) {
         return super.getContent();
     }
 

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/templateengine/semantickernel/blocks/ValBlock.java

@@ -31,8 +31,7 @@ public final class ValBlock extends Block implements TextRendering {
     }
 
     @Override
-    @Nullable
-    public String render(KernelArguments variables) {
+    public String render(@Nullable KernelArguments variables) {
         return value;
     }
 

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/templateengine/semantickernel/blocks/VarBlock.java

@@ -6,6 +6,7 @@ import com.microsoft.semantickernel.orchestration.contextvariables.KernelArgumen
 import com.microsoft.semantickernel.templateengine.semantickernel.TemplateException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import javax.annotation.Nullable;
 
 public final class VarBlock extends Block implements TextRendering {
 
@@ -23,7 +24,7 @@ public final class VarBlock extends Block implements TextRendering {
     }
 
     @Override
-    public String render(KernelArguments variables) {
+    public String render(@Nullable KernelArguments variables) {
         if (variables == null) {
             return "";
         }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/textcompletion/StreamingTextContent.java

@@ -8,8 +8,4 @@ public class StreamingTextContent extends StreamingKernelContent<TextContent> {
         super(content, 0, null, null);
     }
 
-    @Override
-    public byte[] toByteArray() {
-        return new byte[0];
-    }
 }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/textcompletion/TextContent.java

@@ -2,8 +2,6 @@ package com.microsoft.semantickernel.textcompletion;
 
 import com.microsoft.semantickernel.KernelContent;
 import com.microsoft.semantickernel.orchestration.FunctionResultMetadata;
-import com.microsoft.semantickernel.orchestration.contextvariables.ContextVariable;
-import java.util.Map;
 
 public class TextContent extends KernelContent<TextContent> {
 
@@ -21,6 +19,7 @@ public class TextContent extends KernelContent<TextContent> {
         return content;
     }
 
+    @Override
     public String getContent() {
         return content;
     }

java/semantickernel-api/src/main/java/com/microsoft/semantickernel/textcompletion/TextGenerationService.java

@@ -58,8 +58,11 @@ public interface TextGenerationService extends Buildable, TextAIService {
      */
     abstract class Builder implements SemanticKernelBuilder<TextGenerationService> {
 
+        @Nullable
         protected String modelId;
+        @Nullable
         protected OpenAIAsyncClient client;
+        @Nullable
         protected String serviceId;
 
         public Builder withModelId(String modelId) {
@@ -77,6 +80,7 @@ public interface TextGenerationService extends Buildable, TextAIService {
             return this;
         }
 
+        @Override
         public abstract TextGenerationService build();
 
     }