you may use the class o.a.j.core.util.ISO9075 which is currently in a core package.
and for this exact reason ('core') there is also a copy of this class in the o.a.j.util package in the jcr-server contrib...
I'll probably move it to a package that is included with the jackrabbit-commons module in the near future.
just let me know, so i can finally get rid of the copy :) regards angela