code: public void addLockWaiter() {
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled())
              Tr.debug(tc, "addLockWaiter : " + this +
                           ", thread=" + Thread.currentThread().getId());
  
          ivThreadsWaiting = true;
      }
docs: Notify the bean that the current thread will be waiting on the bucket
  lock object, for notification when the bean becomes available for
  use. When {@link #unlock} is called, all waiting threads will be notified
  and may then attempt to obtain the lock again. <p>