PersistentIndex.IndexEntryType getIndexValueType() {
    PersistentIndex.IndexEntryType type = PersistentIndex.IndexEntryType.PUT;
    if (isDelete()) {
      type = PersistentIndex.IndexEntryType.DELETE;
    } else if (isUndelete()) {
      type = PersistentIndex.IndexEntryType.UNDELETE;
    } else if (isTtlUpdate()) {
      type = PersistentIndex.IndexEntryType.TTL_UPDATE;
    }
    return type;
  }
@return {@link PersistentIndex.IndexEntryType} associated with this {@link IndexValue}.
ambry-store/src/main/java/com/github/ambry/store/IndexValue.java