Neither kontact 4.14.1 from Debian jessie, nor kontact 5.4.1 (Version: 4:16.12.1-0neon+16.04+build7) from KDE neon are sending a client ID containing "/Kolab", and so calendars, contact and friends are not listed by kolab because of the guam filtering.
kontact 5.4.1, when setting up an account of type "Kolab groupware server", will send a client id "Kontact IMAP Resource", according to my /var/log/mail.log:
Feb 10 12:10:15 kolab imaps[842]: client id: "name" "Kontact IMAP Resource"
Both versions of kontact work fine with kolab 3.4. In the docs about guam troubleshooting (which I only found because I was curious what guam does, independent of this problem) I would expect a hint how to work around this. If you agree that these kontact versions should be supported by kolab, there should be a more prominent hint in the release notes or setup instructions.
Kontact is smart enough not to list these groupware folders in the e-mail folder view when a kolab groupware account is set up. When an plain IMAP account is set up, these folders are shown (not when guam is active as in kolab 16, of course). However, in this case no client id is sent, as far as I could see from /var/log/mail.log.
Therefore, I think guam should get an additional or updated rule, preventing it from filtering the groupware folders when the client id is "Kontact IMAP Resource".
root@kolab /var/log # dpkg -l pykolab Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name Version Architecture Description +++-==============================================-============================-============================-================================================================================================= ii pykolab 0.8.7-0~kolab1 all Kolab Groupware daemon and utilities