code: private static Optional<ImmutableQueryModifiers> convertModifiers(MutableQueryModifiers queryModifiers) {
          if (queryModifiers.hasModifiers()) {
              ImmutableQueryModifiers immutableQueryModifiers = new ImmutableQueryModifiersImpl(queryModifiers);
              return Optional.of(immutableQueryModifiers);
          } else {
              return Optional.empty();
          }
      }
docs: TODO: explain