public void removeOperatorFromSelection(Operator selectedOperator){
  List<Operator> newList=new ArrayList<>(getSelectedOperators());
  newList.remove(selectedOperator);
  this.selectedOperators=Collections.unmodifiableList(newList);
}

public void removeOperatorFromSelection ( Operator selectedOperator ) { List < Operator > newList = new ArrayList < > ( getSelectedOperators ( ) ) ; newList . remove ( selectedOperator ) ; this . selectedOperators = Collections . unmodifiableList ( newList ) ; }
removes the given operator from the currently selected operators . if the given operator is not selected , does nothing .
