docs: public void deadlockCheck(DeadlockChecker deadlockChecker) {
        if (deadlockChecker == null) {
           return; //no-op
        }
        LockPlaceHolder holder = current;
        if (holder != null) {
           for (LockPlaceHolder pending : pendingRequest) {
              pending.checkDeadlock(deadlockChecker, holder.owner);
           }
        }
     }