code: public void release(T item) {
          HashMap<String,Object> keys = getKeys(item);
  
          synchronized( this ) {
              for( String key : order ) {
                  ConcurrentCache<Object,T> cache = caches.get(key);
  
                  cache.remove(keys.get(key));
              }
          }
      }
docs: Releases the specified item from the cache. If it is still in the persistent
  store, it will be retrieved back into the cache on next query. Otherwise,
  subsequent attempts to search for it in the cache will result in <code>null</code>.
  @param item the item to be released from the cache.