MAINT: change from '_' to '.'

integrationtests/test_data/extroot/realworld_example/dataset_cfoods.yml

@@ -158,8 +158,8 @@ Data:
                       parents:
                         - JSONFile
                       role: File
-                      path: $metadata_json_path
-                      file: $metadata_json_path
+                      path: ${metadata_json.path}
+                      file: ${metadata_json.path}
                   validate: schema/dataset.schema.json
                   subtree:
                     jsondict: