code: public SerializerRegistry registerAbstract(Class<?> abstractType, Class<? extends TypeSerializer> serializer) {
      return registerAbstract(abstractType, calculateTypeId(abstractType), new DefaultTypeSerializerFactory(serializer));
    }
docs: Registers the given class as an abstract serializer for the given abstract type.
  
  @param abstractType The abstract type for which to register the serializer.
  @param serializer The serializer class.
  @return The serializer registry.