protocol handlers for cvs, et al?

http://java.sun.com/j2se/1.5.0/docs/api/java/net/URL.html
http://java.sun.com/javase/6/docs/api/java/net/URL.html
> Protocol handlers for the following protocols are guaranteed to
> exist on the search path :-

>          http, https, ftp, file, and jar

> Protocol handlers for additional protocols may also be available.

but not Out Of The Box. Fortunately protocol handlers are pluggable
(see

http://java.sun.com/developer/onlineTraining/protocolhandlers/

) but I'm wondering if folks can point me to one or more
well-respected Java implementations for scheme=cvs: so I don't hafta
write (and more importantly, test) one. (Extra points for scheme=
{clearcase:, svn:}.)