code: public static byte[] extractQualifier(final byte[] qualifier, 
        final int offset) {
      validateQualifier(qualifier, offset);
      if ((qualifier[offset] & Const.MS_BYTE_FLAG) == Const.MS_BYTE_FLAG) {
        return new byte[] { qualifier[offset], qualifier[offset + 1],
            qualifier[offset + 2], qualifier[offset + 3] };
      } else {
        return new byte[] { qualifier[offset], qualifier[offset + 1] };
      }
    }
docs: Extracts the 2 or 4 byte qualifier from a compacted byte array
  @param qualifier The qualifier to parse
  @param offset An offset within the byte array
  @return A byte array with only the requested qualifier
  @throws IllegalArgumentException if the qualifier is null or the offset falls
  outside of the qualifier array
  @since 2.0