code: public String updateCollection(final Key key) {
          if (key.getCollection() == null && key.getType() == null) {
              throw new IllegalStateException("Key is invalid! " + toString());
          } else if (key.getCollection() == null) {
              key.setCollection(getMappedClass(key.getType()).getCollectionName());
          }
  
          return key.getCollection();
      }
docs: Updates the collection value on a Key with the mapped value on the Key's type Class
  
  @param key the Key to update
  @return the collection name on the Key