@java.lang.Override
  public void writeTo(com.google.protobuf.CodedOutputStream output) throws java.io.IOException {
    for (int i = 0; i < webSearchQueries_.size(); i++) {
      com.google.protobuf.GeneratedMessageV3.writeString(output, 1, webSearchQueries_.getRaw(i));
    }
    if (((bitField0_ & 0x00000001) != 0)) {
      output.writeMessage(4, getSearchEntryPoint());
    }
    for (int i = 0; i < groundingChunks_.size(); i++) {
      output.writeMessage(5, groundingChunks_.get(i));
    }
    for (int i = 0; i < groundingSupports_.size(); i++) {
      output.writeMessage(6, groundingSupports_.get(i));
    }
    if (((bitField0_ & 0x00000002) != 0)) {
      output.writeMessage(7, getRetrievalMetadata());
    }
    getUnknownFields().writeTo(output);
  }
<pre>
Optional. Output only. Retrieval metadata.
</pre>

<code>
optional .google.cloud.vertexai.v1.RetrievalMetadata retrieval_metadata = 7 [(.google.api.field_behavior) = OPTIONAL, (.google.api.field_behavior) = OUTPUT_ONLY];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/GroundingMetadata.java