code: public V remove(Object pKey) {
          TimedEntry<K, V> entry = (TimedEntry<K, V>) entries.remove(pKey);
          return (entry != null) ? entry.getValue() : null;
      }
docs: Removes the mapping for this pKey from this map if present (optional
  operation).
  
  @param pKey pKey whose mapping is to be removed from the map.
  @return previous value associated with specified pKey, or {@code null}
  if there was no mapping for pKey.  A {@code null} return can
  also indicate that the map previously associated {@code null}
  with the specified pKey, if the implementation supports
  {@code null} values.