Serialize payload content types correctly

Author: JordonPhillips

python-packages/aws-event-stream/aws_event_stream/_private/serializers.py

@@ -147,7 +147,7 @@ def begin_struct(self, schema: "Schema") -> Iterator[ShapeSerializer]:
     def _get_payload_member(self, schema: Schema) -> Schema | None:
         for member in schema.members.values():
             if EVENT_PAYLOAD_TRAIT in member.traits:
-                return schema
+                return member
         return None
 
     def _get_payload_media_type(self, schema: Schema, default: str) -> str:

python-packages/aws-event-stream/tests/unit/_private/__init__.py

@@ -526,7 +526,7 @@ def _consumer(schema: Schema, de: ShapeDeserializer) -> None:
                 ":message-type": "event",
                 ":event-type": "payload",
                 "header": "header",
-                ":content-type": "application/json",
+                ":content-type": "text/plain",
             },
             payload=b'"payload"',
         ),