public com.google.protobuf.ByteString getResponseIdBytes() {
      java.lang.Object ref = responseId_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b =
            com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
        responseId_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
<pre>
Output only. response_id is used to identify each response. It is the
encoding of the event_id.
</pre>

<code>string response_id = 13 [(.google.api.field_behavior) = OUTPUT_ONLY];</code>

@return The bytes for responseId.
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/GenerateContentResponse.java