public int addOperator(Operator operator,boolean registerWithProcess){
  if (operator == null) {
    throw new NullPointerException("operator cannot be null!");
  }
  if (operator instanceof ProcessRootOperator) {
    throw new IllegalArgumentException("'Process' operator cannot be added. It must always be the top-level operator!");
  }
  operators.add(operator);
  registerOperator(operator,registerWithProcess);
  return operators.size() - 1;
}

public int addOperator ( Operator operator , boolean registerWithProcess ) { if ( operator == null ) { throw new NullPointerException ( "operator cannot be null!" ) ; } if ( operator instanceof ProcessRootOperator ) { throw new IllegalArgumentException ( "'Process' operator cannot be added. It must always be the top-level operator!" ) ; } operators . add ( operator ) ; registerOperator ( operator , registerWithProcess ) ; return operators . size ( ) - 1 ; }
adds the operator to this execution unit .
