Trival. (#7653)

### What problem does this PR solve?

#7623

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

api/apps/conversation_app.py

@@ -99,6 +99,7 @@ def get():
                     "dataset_id": get_value(ck, "kb_id", "dataset_id"),
                     "image_id": get_value(ck, "image_id", "img_id"),
                     "positions": get_value(ck, "positions", "position_int"),
+                    "doc_type": get_value(ck, "doc_type", "doc_type_kwd"),
                 }
                 for ck in ref.get("chunks", [])
             ]