make extended groups and attribute config fields nullable (fixes #348)

Author: adorton-adobe

user_sync/config.py

@@ -534,11 +534,11 @@ def get_rule_options(self):
         if extension_config:
             after_mapping_hook_text = extension_config.get_string('after_mapping_hook')
             options['after_mapping_hook'] = compile(after_mapping_hook_text, '<per-user after-mapping-hook>', 'exec')
-            options['extended_attributes'] = extension_config.get_list('extended_attributes')
+            options['extended_attributes'] = extension_config.get_list('extended_attributes', True) or []
             # declaration of extended adobe groups: this is needed for two reasons:
             # 1. it allows validation of group names, and matching them to adobe groups
             # 2. it allows removal of adobe groups not assigned by the hook
-            for extended_adobe_group in extension_config.get_list('extended_adobe_groups'):
+            for extended_adobe_group in extension_config.get_list('extended_adobe_groups', True) or []:
                 group = user_sync.rules.AdobeGroup.create(extended_adobe_group)
                 if group is None:
                     message = 'Extension contains illegal extended_adobe_group spec: ' + str(extended_adobe_group)