GenAI upload datetime JSON with warning

Author: aabmass

util/opentelemetry-util-genai/src/opentelemetry/util/genai/_upload/completion_hook.py

@@ -15,6 +15,7 @@
 
 from __future__ import annotations
 
+import datetime
 import json
 import logging
 import posixpath
@@ -287,4 +288,14 @@ class Base64JsonEncoder(json.JSONEncoder):
     def default(self, o: Any) -> Any:
         if isinstance(o, bytes):
             return b64encode(o).decode()
-        return super().default(o)
+        elif isinstance(o, (datetime.datetime, datetime.date)):
+            return o.isoformat()
+
+        try:
+            return super().default(o)
+        except TypeError:
+            _logger.warning(
+                'failed to encode object "%s" to JSON. Falling back to str()',
+                o,
+            )
+            return str(o)