handler.getWaitPrecondition().assertCanWait();
            }
        };
    }

    @Override
    public void cancelBlockedRequests() {
        lock.lock();
        try {
            if (current != null) {
                current.cancelBlockedRequests();
            }
        } finally {
            lock.unlock();
        }
    }

    @Override

     */
    WaitPrecondition getWaitPrecondition();

    /**
     * Releases any blocked requests, in preparation for shutdown.
     */
    void cancelBlockedRequests();

    /**
     * Asserts that this handler has been completed successfully.
     */
    void assertComplete(Collection<Throwable> failures);