fix: bedrock titan embeddings should return usage

Signed-off-by: Gareth Evans <gareth@bryncynfelin.co.uk>

Author: garethjevans

models/spring-ai-bedrock/src/main/java/org/springframework/ai/bedrock/titan/BedrockTitanEmbeddingModel.java

@@ -18,6 +18,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 import java.util.concurrent.atomic.AtomicInteger;
 
 import io.micrometer.observation.Observation;
@@ -28,12 +29,9 @@
 import org.springframework.ai.bedrock.titan.api.TitanEmbeddingBedrockApi;
 import org.springframework.ai.bedrock.titan.api.TitanEmbeddingBedrockApi.TitanEmbeddingRequest;
 import org.springframework.ai.bedrock.titan.api.TitanEmbeddingBedrockApi.TitanEmbeddingResponse;
+import org.springframework.ai.chat.metadata.DefaultUsage;
 import org.springframework.ai.document.Document;
-import org.springframework.ai.embedding.AbstractEmbeddingModel;
-import org.springframework.ai.embedding.Embedding;
-import org.springframework.ai.embedding.EmbeddingOptions;
-import org.springframework.ai.embedding.EmbeddingRequest;
-import org.springframework.ai.embedding.EmbeddingResponse;
+import org.springframework.ai.embedding.*;
 import org.springframework.util.Assert;
 
 /**
@@ -89,6 +87,7 @@ public EmbeddingResponse call(EmbeddingRequest request) {
 
 		List<Embedding> embeddings = new ArrayList<>();
 		var indexCounter = new AtomicInteger(0);
+		int tokenUsage = 0;
 
 		for (String inputContent : request.getInstructions()) {
 			var apiRequest = createTitanEmbeddingRequest(inputContent, request.getOptions());
@@ -111,6 +110,10 @@ public EmbeddingResponse call(EmbeddingRequest request) {
 				}
 
 				embeddings.add(new Embedding(response.embedding(), indexCounter.getAndIncrement()));
+
+				if (response.inputTextTokenCount() != null) {
+					tokenUsage += response.inputTextTokenCount();
+				}
 			}
 			catch (Exception ex) {
 				logger.error("Titan API embedding failed for input at index {}: {}", indexCounter.get(),
@@ -120,7 +123,10 @@ public EmbeddingResponse call(EmbeddingRequest request) {
 			}
 		}
 
-		return new EmbeddingResponse(embeddings);
+		EmbeddingResponseMetadata embeddingResponseMetadata = new EmbeddingResponseMetadata("",
+				getDefaultUsage(tokenUsage));
+
+		return new EmbeddingResponse(embeddings, embeddingResponseMetadata);
 	}
 
 	private TitanEmbeddingRequest createTitanEmbeddingRequest(String inputContent, EmbeddingOptions requestOptions) {
@@ -155,6 +161,10 @@ private String summarizeInput(String input) {
 		return input.length() > 100 ? input.substring(0, 100) + "..." : input;
 	}
 
+	private DefaultUsage getDefaultUsage(int tokens) {
+		return new DefaultUsage(tokens, 0);
+	}
+
 	public enum InputType {
 
 		TEXT, IMAGE