Return dict unchanged when no keys match in RandGridDistortiond

Author: HeyangQin

monai/transforms/spatial/dictionary.py

@@ -2311,8 +2311,7 @@ def __call__(self, data: Mapping[Hashable, torch.Tensor]) -> dict[Hashable, torc
 
         first_key: Hashable = self.first_key(d)
         if first_key == ():
-            out = convert_to_tensor(d, track_meta=get_track_meta())
-            return out
+            return d
         if isinstance(d[first_key], MetaTensor) and d[first_key].pending_operations:  # type: ignore
             warnings.warn(f"data['{first_key}'] has pending operations, transform may return incorrect results.")
         self.rand_grid_distortion.randomize(d[first_key].shape[1:])