final boolean tryMatchData(){
  Object x=item;
  if (x != null && x != this && casItem(x,null)) {
    LockSupport.unpark(waiter);
    return true;
  }
  return false;
}

final boolean tryMatchData ( ) { Object x = item ; if ( x != null && x != this && casItem ( x , null ) ) { LockSupport . unpark ( waiter ) ; return true ; } return false ; }
tries to artificially match a data node - - used by remove .
