Fix 7587: Remove credential_type_id in API v1

awx/api/serializers.py

@@ -343,6 +343,8 @@ class BaseSerializer(serializers.ModelSerializer):
                     continue
                 summary_fields[fk] = OrderedDict()
                 for field in related_fields:
+                    if field == 'credential_type_id' and fk == 'credential' and self.version < 2:
+                        continue
 
                     fval = getattr(fkval, field, None)