@Udf
  public <T> List<T> mapValues(final Map<String, T> input) {
    if (input == null) {
      return null;
    }
    return Lists.newArrayList(input.values());
  }
@Test
  public void shouldReturnEmptyListFromEmptyMap() {
    final Map<String, BigDecimal> input = Maps.newHashMap();
    assertThat(udf.mapValues(input), empty());
  }