code: public void put(Object key, Object value) {
      int weight = getWeight(key) + getWeight(value) + OVERHEAD;
      currentWeight += weight;
      if (cache.put(key, value == null ? NULL_VALUE : value) != null) {
        currentWeight -= weight;
      }
    }
docs: Puts the <code>key/value</code> pair into the cache.
  
  @param key key
  @param value value