Sorry for the mislead. I do have your support case too, Looks like we did not know the correct syntax there.
We just needed %20AND%20 for the join, and it %3D instead of =.
So, a where clause like: contact='foo' and session_type=1 becomes contact%3DU'F4C2A60100EA154695D233F90ABFFD21'%20and%20session_type%3D1
See my working example below:
/caisd-rest/session_log?SORT=login_time DESC&start=1&size=50&rel=all&WC=contact%3DU'F4C2A60100EA154695D233F90ABFFD21'%20and%20session_type%3D1
It was on the same docops page that I mentioned earlier but I totally missed it (REST HTTP Methods - CA Service Management - 17.0 - CA Technologies Documentation )
Hope that resolves yours too
_R