@Test
  public void testDescendingIterator() throws IMQException {
    addValues(region, numValues);
    validateDescendingIterator(indexDataStructure.descendingIterator(null), numValues - 1, 0);
  }
This test will test the descending iterator by iterating the descending iterator and comparing
the results to the test entries in reverse order
geode-core/src/integrationTest/java/org/apache/geode/cache/query/internal/index/MapIndexStoreJUnitTest.java