Add credential info in expanded list view of inventory update

- Fixed issue #2891

Signed-off-by: Hideki Saito <saito@fgrep.org>

awx/api/serializers.py

@@ -2007,17 +2007,22 @@ class InventorySourceOptionsSerializer(BaseSerializer):
     # TODO: remove when old 'credential' fields are removed
     def get_summary_fields(self, obj):
         summary_fields = super(InventorySourceOptionsSerializer, self).get_summary_fields(obj)
+        all_creds = []
         if 'credential' in summary_fields:
             cred = obj.get_cloud_credential()
             if cred:
-                summary_fields['credential'] = {
+                summarized_cred = {
                     'id': cred.id, 'name': cred.name, 'description': cred.description,
                     'kind': cred.kind, 'cloud': True
                 }
+                summary_fields['credential'] = summarized_cred
+                all_creds.append(summarized_cred)
                 if self.version > 1:
                     summary_fields['credential']['credential_type_id'] = cred.credential_type_id
             else:
                 summary_fields.pop('credential')
+        if self.version > 1:
+            summary_fields['credentials'] = all_creds
         return summary_fields
 
 
@@ -5116,4 +5121,3 @@ class ActivityStreamSerializer(BaseSerializer):
         if obj.setting:
             summary_fields['setting'] = [obj.setting]
         return summary_fields
-