docs: protected Iterable<T> queryByField(Object ancestorKey, String fieldName, Object fieldValue) {
      Iterable values = supplier.queryIterable(getCurrentTransaction(), mapper, false, 0, -1,
        ancestorKey, null,
        null, false, null, false,
        Filter.equalsFilter(fieldName, fieldValue));
      return new MappingIterable<T, ID>(mapper, values.iterator());
    }