private boolean verifyZeroed(byte[] arr) {
    for (int i = 0; i < arr.length; i++) {
      if (arr[i] != 0) {
        return false;
      }
    }
    return true;
  }
@param offsetUpto - the entries upto this offset are put into rangeMap, rest are put into offRangeMap
@return the last offset in the rangeMap.
@throws Exception
ambry-tools/src/main/java/com/github/ambry/store/HardDeleteVerifier.java