public Set<AggregationFunctionColumnPair> getFunctionColumnPairs() {
    return _aggregationSpecs.keySet();
  }
@Test
  public void testUniqueFunctionColumnPairs() {
    Set<AggregationFunctionColumnPair> expected = new HashSet<>();
    expected.add(AggregationFunctionColumnPair.fromColumnName("count__*"));
    expected.add(AggregationFunctionColumnPair.fromColumnName("sum__dimX"));

    Configuration metadataProperties = createMetadata(List.of("dimX"), expected);
    StarTreeV2Metadata starTreeV2Metadata = new StarTreeV2Metadata(metadataProperties);
    Set<AggregationFunctionColumnPair> actual = starTreeV2Metadata.getFunctionColumnPairs();
    assertEquals(expected, actual);
  }