public KsqlTransformer<K, GenericRow> getResultMapper() {
    return new ResultTransformer();
  }
@Test
  public void shouldNotMutateParametersOnResultsMap() {
    // Given:
    final GenericRow agg = GenericRow.genericRow(1, 2L, 4);

    // When:
    final GenericRow result = aggregator.getResultMapper().transform("k", agg, ctx);

    // Then:
    assertThat(agg, is(GenericRow.genericRow(1, 2L, 4)));
    assertThat("invalid test", result, is(not(GenericRow.genericRow(1, 2L, 4))));
  }