code: @Trivial
      private void decrementWithheldConcurrency() {
          int w;
          while ((w = withheldConcurrency.get()) > 0 && !withheldConcurrency.compareAndSet(w, w - 1));
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled())
              Tr.debug(this, tc, "withheld concurrency " + w + " --> " + (w == 0 ? 0 : (w - 1)));
      }
docs: Decrement the counter of withheld concurrency only if positive.
  This method should only ever be invoked if the caller is about to enqueue a task to the global executor.
  Otherwise there is a risk of a race condition where withheldConcurrency decrements to 0 with a task still on the queue.