@Override
    public void remove() {
      throw new UnsupportedOperationException("Removing is not supported");
    }
Creates an {@link Iterator} that can iterate through all the index entries in {@code index}.
@param index the {@link PersistentIndex} whose entries need to be iterated on.
ambry-tools/src/main/java/com/github/ambry/store/CompactionVerifier.java