@Udf(description = "Returns Euler's number e raised to the power of an INT value.")
  public Double exp(
      @UdfParameter(
          value = "exponent",
          description = "the exponent to raise e to."
      ) final Integer exponent
  ) {
    return exp(exponent == null ? null : exponent.doubleValue());
  }
@Test
  public void shouldHandleNull() {
    assertThat(udf.exp((Integer) null), is(nullValue()));
    assertThat(udf.exp((Long)null), is(nullValue()));
    assertThat(udf.exp((Double)null), is(nullValue()));
  }