src/main/java/com/workplacesystems/utilsj/collections/TransactionalHashMap.java
@Override
    public V remove(Object key) throws ConcurrentModificationException
    {
        Entry<K,V> e = removeEntryForKey(key);
        return (e == null ? null : e.value);
    }
@Override
    public V remove(Object key) throws ConcurrentModificationException
    {
        Entry<K,V> e = removeEntryForKey(key);
        return (e == null ? null : e.value);
    }
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 <tt>null</tt>
if there was no mapping for key.  A <tt>null</tt> return can
also indicate that the map previously associated <tt>null</tt>
with the specified key.