public static BadRequestException appAlreadyExists(String appId) {
    return new BadRequestException("app already exists for appId:%s", appId);
  }
@Test
  public void testAppAlreadyExists(){
    BadRequestException appAlreadyExists = BadRequestException.appAlreadyExists(appId);
    assertEquals("app already exists for appId:app-1001", appAlreadyExists.getMessage());
  }