@Test
public void testEmptyData() {

  Attribute attribute = new AttributeImpl(FIELD, Collections.emptyList());
  Optional<String> optionalWkt =
      GeometryUtility.createUnionOfGeometryAttribute(
          wktReader, wktWriter, attribute, new GeometryOperator.Context());
  assertThat(optionalWkt.isPresent(), is(false));
}