@Override public final boolean equals(Object obj){
  if (obj == this)   return true;
  if (!(obj instanceof TrelloModel))   return false;
  TrelloModel model=(TrelloModel)obj;
  return !id.equals(ILLEGAL_ID) && id.equals(model.id);
}

@ Override public final boolean equals ( Object obj ) { if ( obj == this ) return true ; if ( ! ( obj instanceof TrelloModel ) ) return false ; TrelloModel model = ( TrelloModel ) obj ; return ! id . equals ( ILLEGAL_ID ) && id . equals ( model . id ) ; }
object can be compared by their unique id .
