public void clearDequeByKey(String key) {
        if (key == null)
            return;

        Map<String, Deque<String>> map = tlMapOfStacks.get();
        if (map == null)
            return;
        Deque<String> deque = map.get(key);
        if (deque == null)
            return;
        deque.clear();
    }
Clear the deque(stack) referenced by 'key'. 

@param key identifies the  stack

@since 2.0.0
slf4j-api/src/main/java/org/slf4j/helpers/ThreadLocalMapOfStacks.java