@Udf
  public String concat(@UdfParameter(
      description = "The varchar fields to concatenate") final String... inputs) {
    if (inputs == null) {
      return null;
    }

    return Arrays.stream(inputs)
        .filter(Objects::nonNull)
        .collect(Collectors.joining());
  }
@Test
  public void shouldReturnSingleInput() {
    assertThat(udf.concat("singular"), is("singular"));
    assertThat(udf.concat(ByteBuffer.wrap(new byte[] {2})), is(ByteBuffer.wrap(new byte[] {2})));
  }