feat: [vertexai] add fluent API in GenerativeModel

java-vertexai/google-cloud-vertexai/src/main/java/com/google/cloud/vertexai/generativeai/GenerativeModel.java

@@ -185,6 +185,41 @@ public Builder setTools(List<Tool> tools) {
     }
   }
 
+  /**
+   * Creates a copy of the current model with updated GenerationConfig.
+   *
+   * @param generationConfig a {@link com.google.cloud.vertexai.api.GenerationConfig} that will be
+   *     used in the new model.
+   * @return a new {@link GenerativeModel} instance with the specified GenerationConfig.
+   */
+  public GenerativeModel withGenerationConfig(GenerationConfig generationConfig) {
+    return new GenerativeModel(modelName, generationConfig, safetySettings, tools, vertexAi);
+  }
+
+  /**
+   * Creates a copy of the current model with updated safetySettings.
+   *
+   * @param safetySettings a list of {@link com.google.cloud.vertexai.api.SafetySetting} that will
+   *     be used in the new model.
+   * @return a new {@link GenerativeModel} instance with the specified safetySettings.
+   */
+  public GenerativeModel withSafetySettings(List<SafetySetting> safetySettings) {
+    return new GenerativeModel(
+        modelName, generationConfig, ImmutableList.copyOf(safetySettings), tools, vertexAi);
+  }
+
+  /**
+   * Creates a copy of the current model with updated tools.
+   *
+   * @param safetySettings a list of {@link com.google.cloud.vertexai.api.Tool} that will be used in
+   *     the new model.
+   * @return a new {@link GenerativeModel} instance with the specified tools.
+   */
+  public GenerativeModel withTools(List<Tool> tools) {
+    return new GenerativeModel(
+        modelName, generationConfig, safetySettings, ImmutableList.copyOf(tools), vertexAi);
+  }
+
   /**
    * Counts tokens in a text message.
    *

java-vertexai/google-cloud-vertexai/src/test/java/com/google/cloud/vertexai/generativeai/GenerativeModelTest.java

@@ -416,6 +416,34 @@ public void testGenerateContentwithDefaultTools() throws Exception {
     assertThat(request.getValue().getTools(0)).isEqualTo(TOOL);
   }
 
+  @Test
+  public void testGenerateContentwithFluentApi() throws Exception {
+    model = new GenerativeModel(MODEL_NAME, vertexAi);
+
+    Field field = VertexAI.class.getDeclaredField("predictionServiceClient");
+    field.setAccessible(true);
+    field.set(vertexAi, mockPredictionServiceClient);
+
+    when(mockPredictionServiceClient.generateContentCallable()).thenReturn(mockUnaryCallable);
+    when(mockUnaryCallable.call(any(GenerateContentRequest.class)))
+        .thenReturn(mockGenerateContentResponse);
+
+    GenerateContentResponse unused =
+        model
+            .withGenerationConfig(GENERATION_CONFIG)
+            .withSafetySettings(safetySettings)
+            .withTools(tools)
+            .generateContent(TEXT);
+
+    ArgumentCaptor<GenerateContentRequest> request =
+        ArgumentCaptor.forClass(GenerateContentRequest.class);
+    verify(mockUnaryCallable).call(request.capture());
+    assertThat(request.getValue().getContents(0).getParts(0).getText()).isEqualTo(TEXT);
+    assertThat(request.getValue().getGenerationConfig()).isEqualTo(GENERATION_CONFIG);
+    assertThat(request.getValue().getSafetySettings(0)).isEqualTo(SAFETY_SETTING);
+    assertThat(request.getValue().getTools(0)).isEqualTo(TOOL);
+  }
+
   @Test
   public void testGenerateContentStreamwithText() throws Exception {
     model = new GenerativeModel(MODEL_NAME, vertexAi);
@@ -569,4 +597,34 @@ public void testGenerateContentStreamwithDefaultTools() throws Exception {
     verify(mockServerStreamCallable).call(request.capture());
     assertThat(request.getValue().getTools(0)).isEqualTo(TOOL);
   }
+
+  @Test
+  public void testGenerateContentStreamwithFluentApi() throws Exception {
+    model = new GenerativeModel(MODEL_NAME, vertexAi);
+
+    Field field = VertexAI.class.getDeclaredField("predictionServiceClient");
+    field.setAccessible(true);
+    field.set(vertexAi, mockPredictionServiceClient);
+
+    when(mockPredictionServiceClient.streamGenerateContentCallable())
+        .thenReturn(mockServerStreamCallable);
+    when(mockServerStreamCallable.call(any(GenerateContentRequest.class)))
+        .thenReturn(mockServerStream);
+    when(mockServerStream.iterator()).thenReturn(mockServerStreamIterator);
+
+    ResponseStream unused =
+        model
+            .withGenerationConfig(GENERATION_CONFIG)
+            .withSafetySettings(safetySettings)
+            .withTools(tools)
+            .generateContentStream(TEXT);
+
+    ArgumentCaptor<GenerateContentRequest> request =
+        ArgumentCaptor.forClass(GenerateContentRequest.class);
+    verify(mockServerStreamCallable).call(request.capture());
+    assertThat(request.getValue().getContents(0).getParts(0).getText()).isEqualTo(TEXT);
+    assertThat(request.getValue().getGenerationConfig()).isEqualTo(GENERATION_CONFIG);
+    assertThat(request.getValue().getSafetySettings(0)).isEqualTo(SAFETY_SETTING);
+    assertThat(request.getValue().getTools(0)).isEqualTo(TOOL);
+  }
 }