docs: IterableOfProtosFluentAssertion<M> usingConfig(FluentEqualityConfig newConfig) {
      Subject.Factory<IterableOfMessagesSubject<M>, Iterable<M>> factory =
          iterableOfMessages(newConfig);
      IterableOfMessagesSubject<M> newSubject = check().about(factory).that(actual());
      if (internalCustomName() != null) {
        newSubject = newSubject.named(internalCustomName());
      }
      return new IterableOfProtosFluentAssertionImpl<M>(newSubject);
    }