Removed GoogleVertexAiChatCompletionResponseEntity and refactored code around it.

Author: lhoet-google

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/googlevertexai/GoogleVertexAiCompletionRequestManager.java

@@ -19,7 +19,6 @@
 import org.elasticsearch.xpack.inference.external.http.sender.UnifiedChatInput;
 import org.elasticsearch.xpack.inference.services.googlevertexai.completion.GoogleVertexAiChatCompletionModel;
 import org.elasticsearch.xpack.inference.services.googlevertexai.request.GoogleVertexAiUnifiedChatCompletionRequest;
-import org.elasticsearch.xpack.inference.services.googlevertexai.response.GoogleVertexAiChatCompletionResponseEntity;
 
 import java.util.Objects;
 import java.util.function.Supplier;
@@ -31,10 +30,7 @@ public class GoogleVertexAiCompletionRequestManager extends GoogleVertexAiReques
     private static final ResponseHandler HANDLER = createGoogleVertexAiResponseHandler();
 
     private static ResponseHandler createGoogleVertexAiResponseHandler() {
-        return new GoogleVertexAiUnifiedChatCompletionResponseHandler(
-            "Google Vertex AI chat completion",
-            GoogleVertexAiChatCompletionResponseEntity::fromResponse
-        );
+        return new GoogleVertexAiUnifiedChatCompletionResponseHandler("Google Vertex AI chat completion");
     }
 
     private final GoogleVertexAiChatCompletionModel model;

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/googlevertexai/GoogleVertexAiUnifiedChatCompletionResponseHandler.java

@@ -41,8 +41,10 @@ public class GoogleVertexAiUnifiedChatCompletionResponseHandler extends GoogleVe
     private static final String ERROR_MESSAGE_FIELD = "message";
     private static final String ERROR_STATUS_FIELD = "status";
 
-    public GoogleVertexAiUnifiedChatCompletionResponseHandler(String requestType, ResponseParser parseFunction) {
-        super(requestType, parseFunction, GoogleVertexAiErrorResponse::fromResponse, true);
+    private static final ResponseParser noopParseFunction = (a, b) -> null;
+
+    public GoogleVertexAiUnifiedChatCompletionResponseHandler(String requestType) {
+        super(requestType, noopParseFunction, GoogleVertexAiErrorResponse::fromResponse, true);
     }
 
     @Override

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/services/googlevertexai/response/GoogleVertexAiChatCompletionResponseEntity.java

@@ -33,10 +33,7 @@ public class GoogleVertexAiUnifiedChatCompletionResponseHandlerTests extends EST
     private static final String INFERENCE_ID = "vertexAiInference";
 
     private final GoogleVertexAiUnifiedChatCompletionResponseHandler responseHandler =
-        new GoogleVertexAiUnifiedChatCompletionResponseHandler(
-            "chat_completion",
-            (parser, xContentRegistry) -> mock() // Dummy parse function, not used in these error tests
-        );
+        new GoogleVertexAiUnifiedChatCompletionResponseHandler("chat_completion");
 
     public void testFailValidationWithAllErrorFields() throws IOException {
         var responseJson = """