I haven't had time to analyze the source code, but the change in `etc/kamailio.cfg` should not be done, the new attribute has to be added to the core cookbook in the wiki (after the merge). The listen has other attributes (e.g., name), not all have to be listed in the default config file and the new one is probably not going to be commonly used.
Also, is it sure it is needed to be added in `ims_ipsec_pcscf`?