public void addOperator(Operator operator,int index){
  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(index,operator);
  registerOperator(operator,true);
}

public void addOperator ( Operator operator , int index ) { 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 ( index , operator ) ; registerOperator ( operator , true ) ; }
adds the operator to this execution unit . the operator at this index and all subsequent operators are shifted to the right . the operator is registered automatically .
