public java.lang.String getRequestId() {
    java.lang.Object ref = requestId_;
    if (ref instanceof java.lang.String) {
      return (java.lang.String) ref;
    } else {
      com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
      java.lang.String s = bs.toStringUtf8();
      requestId_ = s;
      return s;
    }
  }
public java . lang . String getRequestId ( ) { java . lang . Object ref = requestId_ ; if ( ref instanceof java . lang . String ) { return ( java . lang . String ) ref ; } else { com . google . protobuf . ByteString bs = ( com . google . protobuf . ByteString ) ref ; java . lang . String s = bs . toStringUtf8 ( ) ; requestId_ = s ; return s ; } }
<pre>
Optional. A unique id used to identify the request. If the server
receives two
[CreateClusterRequest][google.cloud.dataproc.v1.CreateClusterRequest]
requests  with the same id, then the second request will be ignored and the
first [google.longrunning.Operation][google.longrunning.Operation] created
and stored in the backend is returned.
It is recommended to always set this value to a
[UUID](https://en.wikipedia.org/wiki/Universally_unique_identifier).
The id must contain only letters (a-z, A-Z), numbers (0-9),
underscores (_), and hyphens (-). The maximum length is 40 characters.
</pre>

<code>string request_id = 4;</code>