Appending into ByteStringBuilder fail if initial array blank

ByteStringBuilder cannot append codepoints 0xD8xx (lonely surrogates). It should - StringBuilder.appendCodePoint() work with it.
(Problem is only with uncomplete/nonvalid unicode strings, so it is not critical problem.)

Mentioned in: https://github.com/wildfly-security/wildfly-elytron/pull/101

UPDATE:
ByteStringBuilder encode surrogates correctly by RFC3629 (if we ignore they are prohibited because they are reserved for UTF-16). Conversly StringBuilder and (char) operator encode D800-D8FF bad as 3F.

Problem is only in appending into ByteStringBuilder constructed as:

    new ByteStringBuilder(new byte[]{});