@Override
 public int hashCode() {
   final int prime = 31;
   int result = 1;
   result = prime * result + ((unit == null) ? 0 : unit.hashCode());
   result = prime * result + ((value == null) ? 0 : value.hashCode());
   return result;
 }
 @Override
 public int hashCode() {
   final int prime = 31;
   int result = 1;
   result = prime * result + ((expr == null) ? 0 : expr.hashCode());
   result = prime * result + (not ? 1231 : 1237);
   result = prime * result + ((targetList == null) ? 0 : targetList.hashCode());
   return result;
 }