@Override
  PersistentIndex.IndexEntryType getResetKeyType() {
    if (getVersion() == PersistentIndex.VERSION_0) {
      return null;
    } else {
      return super.getResetKeyType();
    }
  }
Mock {@link IndexSegment} that uses non-{@link PersistentIndex#CURRENT_VERSION}
ambry-store/src/test/java/com/github/ambry/store/IndexSegmentTest.java