https://bugzilla.redhat.com/docs/en/html/api/extensions/ExternalBugs/lib/WebService.html#add_external_bug Mentions a parameter: ext_bz_type_id this should be ext_type_id Mentioning that the 'Webservice Group' these methods belong to would be helpful too. I eventually reverse-engineered the 'Group' to be ExternalBugs.* as in ExternalBugs.add_external_bug ExternalBugs.delete_external_bug etc. Also (less important) an example or two would be *very* helpful.
ext_bz_type_id error will be fixed in Bugzilla 4.2.2-4, so this is just to mention the webservice group.