docs: private static byte[] getQualifier(final long start_time) {
      if (start_time < 1) {
        throw new IllegalArgumentException("The start timestamp has not been set");
      }
      
      final long base_time;
      final byte[] qualifier;
      long timestamp = start_time;
      // downsample to seconds to save space AND prevent duplicates if the time
      // is on a second boundary (e.g. if someone posts at 1328140800 with value A 
      // and 1328140800000L with value B)
      if (timestamp % 1000 == 0) {
        timestamp = timestamp / 1000;
      }
      
      if ((timestamp & Const.SECOND_MASK) != 0) {
        // drop the ms timestamp to seconds to calculate the base timestamp
        base_time = ((timestamp / 1000) - 
            ((timestamp / 1000) % Const.MAX_TIMESPAN));
        qualifier = new byte[5];
        final int offset = (int) (timestamp - (base_time * 1000));
        System.arraycopy(Bytes.fromInt(offset), 0, qualifier, 1, 4);
      } else {
        base_time = (timestamp - (timestamp % Const.MAX_TIMESPAN));
        qualifier = new byte[3];
        final short offset = (short) (timestamp - base_time);
        System.arraycopy(Bytes.fromShort(offset), 0, qualifier, 1, 2);
      }
      qualifier[0] = PREFIX;
      return qualifier;
    }