Method poll

src/main/java/cms/utils/UniqueBlockingQueue.java:144–151

()

	}
	
	@Override
	public T poll() {
	    T e = mBlockingQueue.poll();
	    if (e != null) {
	    	mElementSet.remove(e);
	    }
	    return e;
	}
	
	@Override
	public T poll(long timeout, TimeUnit unit) throws InterruptedException {