code: public V get(ResourceType type, PoolInfo poolInfo) {
      Map<PoolInfo, V> poolInfoMap = typePoolInfoMap.get(type);
      if (poolInfoMap == null) {
        return null;
      }
      return poolInfoMap.get(poolInfo);
    }
docs: Get the value with the appropriate keys
  
  @param type Resource type
  @param poolInfo Pool info
  @param value Value to put
  @return Previous value, can be null if if wasn't set