private List<HardDeletePersistItem> getHardDeletePersistItemList() {
      return items;
    }
Compare two StoreFindTokens and return the result as an integer like compareTo interface.
These two tokens have to be IndexBased tokens.
@param token1 The first token to compare.
@param token2 The second token to compare.
@return 0 means they are equal. negative number means token1 is less than token2. positive number means the opposite.
ambry-store/src/main/java/com/github/ambry/store/HardDeleter.java