@Udf(description = "Converts the number of milliseconds since 1970-01-01 00:00:00 UTC/GMT into "
      + "a TIMESTAMP value.")
  public Timestamp fromUnixTime(
      @UdfParameter(
          description = "Milliseconds since"
              + " January 1, 1970, 00:00:00 GMT.") final Long epochMilli
  ) {
    if (epochMilli == null) {
      return null;
    }
    return new Timestamp(epochMilli);
  }
@Test
  public void shouldConvertToTimestamp() {
    // When:
    final Object result = udf.fromUnixTime(100L);

    // Then:
    assertThat(result, is(new Timestamp(100L)));
  }