@Override
      long toLong(byte[] bytes, int offset, int length) {
        long l = 0;
        for (int i = offset; i < offset + length; i++) {
          l <<= 8;
          l ^= bytes[i] & 0xFF;
        }
        return l;
      }
Returns the Unsafe-using Converter, or falls back to the pure-Java implementation if unable
to do so.
hbase-common/src/main/java/org/apache/hadoop/hbase/util/Bytes.java