A DN may contain RDNs that are separated by semi colons. Looks like the current code doesn't handle this correctly.
I believe this can be fixed by changing the following lines in Dn.parseDn method:
Line 104 from:
case char == ',' || char == '+':
to:
case char == ',' || char == '+' || char == ';':

Line 112 from:
if char == ',' {
to:
if char == ',' || char == ';' {