code: protected void returnToPool() {
          CacheEntryPool cep = cacheEntryPool;
          // An assertion failure here means this CE is being
          // returned to the pool while in use and this
          // should never be the case;
          assert refCount.get() == 0;
          if (lruHead != null)
              lruHead.remove(this);
          reset();
          cep.add(this);
      }
docs: ---------------------------------