src/main/java/com/workplacesystems/utilsj/collections/TransactionalBidiTreeMap.java
@Override
    public V remove(final Object key)
	throws ConcurrentModificationException {

        checkKey(key);

        return (V)doRemove(key, KEY);
    }
@Override
    public V remove(final Object key)
	throws ConcurrentModificationException {

        checkKey(key);

        return (V)doRemove(key, KEY);
    }
Removes the mapping for this key from this map if present

@param key key whose mapping is to be removed from the map.

@return previous value associated with specified key, or null
if there was no mapping for key.