@Override
  public void validate(String value, @Nullable List<String> options) {
    checkRequest(StringUtils.equalsIgnoreCase(value, "true") || StringUtils.equalsIgnoreCase(value, "false"),
      "Value '%s' must be one of \"true\" or \"false\".", value);
  }
@Test
  public void fail_on_invalid_boolean() {
    assertThatThrownBy(() -> underTest.validate("abc", null))
      .isInstanceOf(BadRequestException.class)
      .hasMessage("Value 'abc' must be one of \"true\" or \"false\".");
  }