assertNull(converter.reverse().convert(null));

    assertEquals((Integer) 5, converter.convert("5"));
    assertEquals("5", converter.reverse().convert(5));
  }

  // Null-passthrough violates our nullness annotations, so we don't support it under J2KT.
  @J2ktIncompatible
  public void testNullIsPassedThrough() {
    Converter<String, String> nullsArePassed = sillyConverter(false);

                                Valid Options: LEAST_CONN, RANDOM, PASSTHROUGH, ROUND_ROBIN, LEAST_REQUEST
                              enum:
                              - UNSPECIFIED
                              - LEAST_CONN
                              - RANDOM
                              - PASSTHROUGH
                              - ROUND_ROBIN
                              - LEAST_REQUEST