@Udf
  public <T> Integer calcArrayLength(
      @UdfParameter(description = "The array") final List<T> array
  ) {
    if (array == null) {
      return null;
    }
    return array.size();
  }
@Test
  public void shouldReturnArraySize() {
    assertThat(udf.calcArrayLength(ImmutableList.of()), is(0));
    assertThat(udf.calcArrayLength(ImmutableList.of(1)), is(1));
    assertThat(udf.calcArrayLength(ImmutableList.of("one", "two")), is(2));
  }