code: public void setUidHash(String uidHash) {
  
  		Preconditions.checkNotNull(uidHash);
  		Preconditions.checkArgument(uidHash.matches("^[0-9A-Fa-f]{32}$"),
  				"Node hash must be a 32 character String that describes a hex code. Found: " + uidHash);
  
  		this.userProvidedNodeHash = uidHash;
  	}
docs: Sets an user provided hash for this operator. This will be used AS IS the create the
  JobVertexID.
  
  <p>The user provided hash is an alternative to the generated hashes, that is considered when
  identifying an operator through the default hash mechanics fails (e.g. because of changes
  between Flink versions).
  
  <p><strong>Important</strong>: this should be used as a workaround or for trouble shooting.
  The provided hash needs to be unique per transformation and job. Otherwise, job submission
  will fail. Furthermore, you cannot assign user-specified hash to intermediate nodes in an
  operator chain and trying so will let your job fail.
  
  <p>A use case for this is in migration between Flink versions or changing the jobs in a way
  that changes the automatically generated hashes. In this case, providing the previous hashes
  directly through this method (e.g. obtained from old logs) can help to reestablish a lost
  mapping from states to their target operator.
  
  @param uidHash The user provided hash for this operator. This will become the JobVertexID, which is shown in the
  logs and web ui.