Don't strip out null's in serialized events, as that is not need anymore and...

Don't strip out null's in serialized events, as that is not need anymore and it's not in the spec (yet)

synapse/api/events/__init__.py

@@ -22,7 +22,8 @@ def serialize_event(hs, e):
     if not isinstance(e, SynapseEvent):
         return e
 
-    d = {k: v for k, v in e.get_dict().items() if v is not None}
+    # Should this strip out None's?
+    d = {k: v for k, v in e.get_dict().items()}
     if "age_ts" in d:
         d["age"] = int(hs.get_clock().time_msec()) - d["age_ts"]
         del d["age_ts"]