@Override
  public String printAll() {
    StringBuilder sb = new StringBuilder();
    for (final Object item : valueToEntriesMap.entrySet()) {
      Entry mapEntry = (Entry) item;
      sb.append("Key: " + mapEntry.getKey());
      Object value = mapEntry.getValue();
      if (value instanceof Collection) {
        for (final Object o : (Collection) value) {
          sb.append(" Value:" + getTargetObject((RegionEntry) o));
        }
      } else {
        sb.append(" Value:" + getTargetObject((RegionEntry) value));
      }

      sb.append("\n");

    }
    return sb.toString();
  }
returns a new InMemoryIndexStorageEntry with current index key and its next value which is
the next RE in the collection. Make sure hasNext() has been called before calling this method
geode-core/src/main/java/org/apache/geode/cache/query/internal/index/MemoryIndexStore.java