@ScalarFunction
  public static boolean isJson(String inputStr) {
    try {
      JsonUtils.stringToJsonNode(inputStr);
      return true;
    } catch (Exception e) {
      return false;
    }
  }
@Test(dataProvider = "isJson")
  public void testIsJson(String input, boolean expectedValue) {
    assertEquals(StringFunctions.isJson(input), expectedValue);
  }