@Udf
  public <T extends Comparable<? super T>> List<T> arraySortDefault(@UdfParameter(
      description = "The array to sort") final List<T> input) {
    return arraySortWithDirection(input, "ASC");
  }
@Test
  public void shouldReturnNullForNullInput() {
    assertThat(udf.arraySortDefault((List<String>) null), is(nullValue()));
  }