docs: public <S, D> TypeMap<S, D> emptyTypeMap(Class<S> sourceType, Class<D> destinationType) {
      Assert.notNull(sourceType, "sourceType");
      Assert.notNull(destinationType, "destinationType");
      Assert.isNull(config.typeMapStore.get(sourceType, destinationType, null), "TypeMap already defined");
      return config.typeMapStore.createEmptyTypeMap(sourceType, destinationType, null, config, engine);
    }