code: public static Node createStatusUpdateNode(final String statusUpdateId) {
  		if (INDEX_STATUS_UPDATES.get(IDENTIFIER, statusUpdateId).getSingle() == null) {
  			final Node statusUpdate = DATABASE.createNode();
  			statusUpdate.setProperty(Properties.StatusUpdate.IDENTIFIER,
  					statusUpdateId);
  			INDEX_STATUS_UPDATES.add(statusUpdate, IDENTIFIER, statusUpdateId);
  			return statusUpdate;
  		}
  
  		throw new IllegalArgumentException(
  				"status update node with identifier \"" + statusUpdateId
  						+ "\" already existing!");
  	}
docs: create a status update node in the active database
  
  @param statusUpdateId
  status update identifier
  @return status update node having its identifier stored
  @throws IllegalArgumentException
  if the identifier is already in use