Add refusal field to ChatCompletionMessage and related classes

- Updated OpenAiChatModel, OpenAiApi, and OpenAiStreamFunctionCallingHelper to include the `refusal` field in metadata.
- Adjusted constructors and methods to handle the new `refusal` attribute.
- Modified related tests to account for the new `refusal` field.
- Add the refusal field value to the Spring AI AssistantMessage metadata

Resolves #1178

models/spring-ai-openai/src/main/java/org/springframework/ai/openai/OpenAiChatModel.java

@@ -241,12 +241,13 @@ public ChatResponse call(Prompt prompt) {
 
 				List<Generation> generations = choices.stream().map(choice -> {
 			// @formatter:off
-						Map<String, Object> metadata = Map.of(
-								"id", chatCompletion.id() != null ? chatCompletion.id() : "",
-								"role", choice.message().role() != null ? choice.message().role().name() : "",
-								"index", choice.index(),
-								"finishReason", choice.finishReason() != null ? choice.finishReason().name() : "");
-						// @formatter:on
+					Map<String, Object> metadata = Map.of(
+							"id", chatCompletion.id() != null ? chatCompletion.id() : "",
+							"role", choice.message().role() != null ? choice.message().role().name() : "",
+							"index", choice.index(),
+							"finishReason", choice.finishReason() != null ? choice.finishReason().name() : "",
+							"refusal", StringUtils.hasText(choice.message().refusal()) ? choice.message().refusal() : "");
+					// @formatter:on
 					return buildGeneration(choice, metadata);
 				}).toList();
 
@@ -313,7 +314,8 @@ public Flux<ChatResponse> stream(Prompt prompt) {
 									"id", chatCompletion2.id(),
 									"role", roleMap.getOrDefault(id, ""),
 									"index", choice.index(),
-									"finishReason", choice.finishReason() != null ? choice.finishReason().name() : "");
+									"finishReason", choice.finishReason() != null ? choice.finishReason().name() : "",
+									"refusal", StringUtils.hasText(choice.message().refusal()) ? choice.message().refusal() : "");
 
 							return buildGeneration(choice, metadata);
 						}).toList();
@@ -453,7 +455,7 @@ else if (message.getMessageType() == MessageType.ASSISTANT) {
 					}).toList();
 				}
 				return List.of(new ChatCompletionMessage(assistantMessage.getContent(),
-						ChatCompletionMessage.Role.ASSISTANT, null, null, toolCalls));
+						ChatCompletionMessage.Role.ASSISTANT, null, null, toolCalls, null));
 			}
 			else if (message.getMessageType() == MessageType.TOOL) {
 				ToolResponseMessage toolMessage = (ToolResponseMessage) message;
@@ -466,7 +468,7 @@ else if (message.getMessageType() == MessageType.TOOL) {
 				return toolMessage.getResponses()
 					.stream()
 					.map(tr -> new ChatCompletionMessage(tr.responseData(), ChatCompletionMessage.Role.TOOL, tr.name(),
-							tr.id(), null))
+							tr.id(), null, null))
 					.toList();
 			}
 			else {

models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiApi.java

@@ -560,7 +560,8 @@ public record ChatCompletionMessage(// @formatter:off
 			@JsonProperty("role") Role role,
 			@JsonProperty("name") String name,
 			@JsonProperty("tool_call_id") String toolCallId,
-			@JsonProperty("tool_calls") List<ToolCall> toolCalls) {// @formatter:on
+			@JsonProperty("tool_calls") List<ToolCall> toolCalls,
+			@JsonProperty("refusal") String refusal) {// @formatter:on
 
 		/**
 		 * Get message content as String.
@@ -582,7 +583,7 @@ public String content() {
 		 * @param role The role of the author of this message.
 		 */
 		public ChatCompletionMessage(Object content, Role role) {
-			this(content, role, null, null, null);
+			this(content, role, null, null, null, null);
 		}
 
 		/**

models/spring-ai-openai/src/main/java/org/springframework/ai/openai/api/OpenAiStreamFunctionCallingHelper.java

@@ -91,6 +91,7 @@ private ChatCompletionMessage merge(ChatCompletionMessage previous, ChatCompleti
 		role = (role != null ? role : Role.ASSISTANT); // default to ASSISTANT (if null
 		String name = (current.name() != null ? current.name() : previous.name());
 		String toolCallId = (current.toolCallId() != null ? current.toolCallId() : previous.toolCallId());
+		String refusal = (current.refusal() != null ? current.refusal() : previous.refusal());
 
 		List<ToolCall> toolCalls = new ArrayList<>();
 		ToolCall lastPreviousTooCall = null;
@@ -120,7 +121,7 @@ private ChatCompletionMessage merge(ChatCompletionMessage previous, ChatCompleti
 				toolCalls.add(lastPreviousTooCall);
 			}
 		}
-		return new ChatCompletionMessage(content, role, name, toolCallId, toolCalls);
+		return new ChatCompletionMessage(content, role, name, toolCallId, toolCalls, refusal);
 	}
 
 	private ToolCall merge(ToolCall previous, ToolCall current) {

models/spring-ai-openai/src/test/java/org/springframework/ai/openai/api/tool/OpenAiApiToolFunctionCallIT.java

@@ -122,7 +122,7 @@ public void toolFunctionCall() {
 
 					// extend conversation with function response.
 					messages.add(new ChatCompletionMessage("" + weatherResponse.temp() + weatherRequest.unit(),
-							Role.TOOL, functionName, toolCall.id(), null));
+							Role.TOOL, functionName, toolCall.id(), null, null));
 				}
 			}