code: public static <V> Optional<V> associated(Associator associator,
              Class<V> type, Serializable id) {
          return associator.associated(new TypedIdKey<>(type, id), type);
      }
docs: Retrieves a value with the given type and id from the given associator.
  
  @param <V> the value type
  @param associator the associator
  @param type the type
  @param id the id
  @return the associated value, if any