Copy metadata in ChatResponse Builder's from() method

 - Update ChatResponse.Builder to copy all metadata fields when using from()
 - Expand test case to verify correct metadata copying in QA advisor

 Resolves #1537

Author: tzolov

spring-ai-core/src/main/java/org/springframework/ai/chat/model/ChatResponse.java

@@ -125,6 +125,11 @@ private Builder() {
 
 		public Builder from(ChatResponse other) {
 			this.generations = other.generations;
+			this.chatResponseMetadataBuilder.withModel(other.chatResponseMetadata.getModel());
+			this.chatResponseMetadataBuilder.withId(other.chatResponseMetadata.getId());
+			this.chatResponseMetadataBuilder.withRateLimit(other.chatResponseMetadata.getRateLimit());
+			this.chatResponseMetadataBuilder.withUsage(other.chatResponseMetadata.getUsage());
+			this.chatResponseMetadataBuilder.withPromptMetadata(other.chatResponseMetadata.getPromptMetadata());
 			Set<Map.Entry<String, Object>> entries = other.chatResponseMetadata.entrySet();
 			for (Map.Entry<String, Object> entry : entries) {
 				this.chatResponseMetadataBuilder.withKeyValue(entry.getKey(), entry.getValue());

spring-ai-core/src/test/java/org/springframework/ai/chat/client/advisor/QuestionAnswerAdvisorTests.java

@@ -19,7 +19,9 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.when;
 
+import java.time.Duration;
 import java.util.List;
+import java.util.Map;
 
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
@@ -28,8 +30,12 @@
 import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 import org.springframework.ai.chat.client.ChatClient;
+import org.springframework.ai.chat.messages.AssistantMessage;
 import org.springframework.ai.chat.messages.Message;
 import org.springframework.ai.chat.messages.MessageType;
+import org.springframework.ai.chat.metadata.ChatResponseMetadata;
+import org.springframework.ai.chat.metadata.DefaultUsage;
+import org.springframework.ai.chat.metadata.RateLimit;
 import org.springframework.ai.chat.model.ChatModel;
 import org.springframework.ai.chat.model.ChatResponse;
 import org.springframework.ai.chat.model.Generation;
@@ -60,8 +66,50 @@ public class QuestionAnswerAdvisorTests {
 	@Test
 	public void qaAdvisorWithDynamicFilterExpressions() {
 
+		// @formatter:off
 		when(chatModel.call(promptCaptor.capture()))
-			.thenReturn(new ChatResponse(List.of(new Generation("Your answer is ZXY"))));
+			.thenReturn(new ChatResponse(List.of(new Generation(new AssistantMessage("Your answer is ZXY"))),
+				ChatResponseMetadata.builder()
+					.withId("678")
+					.withModel("model1")
+					.withKeyValue("key6", "value6")
+					.withMetadata(Map.of("key1","value1" ))
+					.withPromptMetadata(null)
+					.withRateLimit(new RateLimit() {
+
+						@Override
+						public Long getRequestsLimit() {
+							return 5l;
+						}
+
+						@Override
+						public Long getRequestsRemaining() {
+							return 6l;
+						}
+
+						@Override
+						public Duration getRequestsReset() {
+							return Duration.ofSeconds(7);
+						}
+
+						@Override
+						public Long getTokensLimit() {
+							return 8l;
+						}
+
+						@Override
+						public Long getTokensRemaining() {
+							return 8l;
+						}
+
+						@Override
+						public Duration getTokensReset() {
+							return Duration.ofSeconds(9);
+						}
+					})
+					.withUsage(new DefaultUsage(6l, 7l))
+					.build()));
+		// @formatter:on
 
 		when(vectorStore.similaritySearch(vectorSearchCaptor.capture()))
 			.thenReturn(List.of(new Document("doc1"), new Document("doc2")));
@@ -75,13 +123,33 @@ public void qaAdvisorWithDynamicFilterExpressions() {
 			.build();
 
 		// @formatter:off
-		var content = chatClient.prompt()
+		var response = chatClient.prompt()
 			.user("Please answer my question XYZ")
 			.advisors(a -> a.param(QuestionAnswerAdvisor.FILTER_EXPRESSION, "type == 'Spring'"))
 			.call()
-			.content();
+			.chatResponse();
 		//formatter:on
 
+		// Ensure the metadata is correctly copied over
+		assertThat(response.getMetadata().getModel()).isEqualTo("model1");
+		assertThat(response.getMetadata().getId()).isEqualTo("678");
+		assertThat(response.getMetadata().getRateLimit().getRequestsLimit()).isEqualTo(5l);
+		assertThat(response.getMetadata().getRateLimit().getRequestsRemaining()).isEqualTo(6l);
+		assertThat(response.getMetadata().getRateLimit().getRequestsReset()).isEqualTo(Duration.ofSeconds(7));
+		assertThat(response.getMetadata().getRateLimit().getTokensLimit()).isEqualTo(8l);
+		assertThat(response.getMetadata().getRateLimit().getTokensRemaining()).isEqualTo(8l);
+		assertThat(response.getMetadata().getRateLimit().getTokensReset()).isEqualTo(Duration.ofSeconds(9));
+		assertThat(response.getMetadata().getUsage().getPromptTokens()).isEqualTo(6l);
+		assertThat(response.getMetadata().getUsage().getGenerationTokens()).isEqualTo(7l);
+		assertThat(response.getMetadata().getUsage().getTotalTokens()).isEqualTo(6l + 7l);
+		assertThat(response.getMetadata().get("key6").toString()).isEqualTo("value6");
+		assertThat(response.getMetadata().get("key1").toString()).isEqualTo("value1");
+		
+
+		
+
+		String content = response.getResult().getOutput().getContent();
+
 		assertThat(content).isEqualTo("Your answer is ZXY");
 
 		Message systemMessage = promptCaptor.getValue().getInstructions().get(0);
@@ -112,5 +180,7 @@ public void qaAdvisorWithDynamicFilterExpressions() {
 		assertThat(vectorSearchCaptor.getValue().getFilterExpression()).isEqualTo(new FilterExpressionBuilder().eq("type", "Spring").build());
 		assertThat(vectorSearchCaptor.getValue().getSimilarityThreshold()).isEqualTo(0.99d);
 		assertThat(vectorSearchCaptor.getValue().getTopK()).isEqualTo(6);
+
+
 	}
 }