@Override
  public CloseableIterator<CachedDeserializable> descendingKeyIterator() {
    return new KeyItr(map.descendingMap().entrySet().iterator());
  }
A dummy implementation of an IndexMap. Keeps all of the entries in memory, but in serialized
form.
geode-core/src/main/java/org/apache/geode/internal/cache/persistence/query/mock/IndexMapImpl.java