private ERXMutableInteger _decrementReferenceCounterForKey(String key) {
    ERXMutableInteger count = (ERXMutableInteger) _referenceCounters().objectForKey(key);
    if (count != null) count.decrement();

    if (log.isDebugEnabled())
      log.debug("_decrementReferenceCounterForKey() - count = " + count + ", key = " + key);
    return count;
  }