Make sure to only encode version_info in json if available

python/podio_gen/generator_utils.py

@@ -5,6 +5,7 @@
 
 import re
 import json
+from copy import deepcopy
 
 
 def _get_namespace_class(full_type):
@@ -324,7 +325,11 @@ def __init__(
     def _to_json(self):
         """Return the dictionary, so that we can easily hook this into the pythons
         JSON ecosystem"""
-        return self.__dict__
+        definition = deepcopy(self.__dict__)
+        # Only dump the version information if it's populated
+        if definition["version_info"] is None:
+            del definition["version_info"]
+        return definition
 
 
 class DataModelJSONEncoder(json.JSONEncoder):