code: public StorageComponent<KeyType, ValueType> getStorageComponent(final KeyType key) {
  
          KeyToStorageComponent<KeyType, ValueType> storage = getkeyToStorage();
          StorageComponent<KeyType, ValueType> storageComponent = storage.get(key);
          if (storageComponent == null) {
              storageComponent = new StorageComponent<KeyType, ValueType>();
              storage.put(key, storageComponent);
          }
          return storageComponent;
      }
docs: Returns child StorageComponent by given key.
  
  @param key
  the key of children StorageComponent.
  @return a StorageComponent object.