public com.google.protobuf.ByteString getRequestIdBytes() {
      java.lang.Object ref = requestId_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b =
            com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
        requestId_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
<pre>
Global request identifier auto-generated by the API.
</pre>

<code>string request_id = 9 [(.google.api.field_info) = { ... }</code>

@return The bytes for requestId.
java-speech/proto-google-cloud-speech-v2/src/main/java/com/google/cloud/speech/v2/RecognitionResponseMetadata.java