@Udf
  public Integer abs(@UdfParameter final Integer val) {
    return (val == null) ? null : Math.abs(val);
  }
@Test
  public void shouldHandleNegative() {
    assertThat(udf.abs(-1), is(1));
    assertThat(udf.abs(-1L), is(1L));
    assertThat(udf.abs(-1.0), is(1.0));
    assertThat(udf.abs(new BigDecimal(-1)), is(new BigDecimal(-1).abs()));
  }