public java.lang.String getRequestId() {
      java.lang.Object ref = requestId_;
      if (!(ref instanceof java.lang.String)) {
        com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        requestId_ = s;
        return s;
      } else {
        return (java.lang.String) ref;
      }
    }
<pre>
Optional. The request ID must be a valid UUID with the exception that
zero UUID is not supported (00000000-0000-0000-0000-000000000000).
</pre>

<code>string request_id = 3 [(.google.api.field_behavior) = OPTIONAL];</code>

@return The requestId.
java-vmwareengine/proto-google-cloud-vmwareengine-v1/src/main/java/com/google/cloud/vmwareengine/v1/UpdateClusterRequest.java