@Udf
  public Integer abs(@UdfParameter final Integer val) {
    return (val == null) ? null : Math.abs(val);
  }
@Test
  public void shouldHandleNull() {
    assertThat(udf.abs((Integer) null), is(nullValue()));
    assertThat(udf.abs((Long)null), is(nullValue()));
    assertThat(udf.abs((Double)null), is(nullValue()));
    assertThat(udf.abs((BigDecimal) null), is(nullValue()));
  }