code: public static <T extends Tag, V> void unregister(Class<T> tag, Class<V> type) {
          tagToConverter.remove(tag);
          typeToConverter.remove(type);
      }
docs: Unregisters a converter.
  
  @param <T>  Tag type to unregister.
  @param <V>  Value type to unregister.
  @param tag  Tag type class to unregister.
  @param type Value type class to unregister.