code: private static void validateQualifier(final byte[] qualifier, 
        final int offset) {
      if (offset < 0 || offset >= qualifier.length - 1) {
        throw new IllegalDataException("Offset of [" + offset + 
            "] is out of bounds for the qualifier length of [" + 
            qualifier.length + "]");
      }
    }
docs: Checks the qualifier to verify that it has data and that the offset is
  within bounds
  @param qualifier The qualifier to validate
  @param offset An optional offset
  @throws IllegalDataException if the qualifier is null or the offset falls
  outside of the qualifier array
  @since 2.0