Remove unused LockFile and FilePermissions classes from old caching code

csp/impl/struct.py

@@ -105,18 +105,12 @@ def collectts(cls, **kwargs):
 
         return csp.struct_collectts(cls, kwargs)
 
-    @classmethod
-    def _postprocess_dict_to_python(cls, d):
-        return d
-
     @classmethod
     def _obj_to_python(cls, obj):
         if isinstance(obj, Struct):
-            return obj._postprocess_dict_to_python(
-                {k: cls._obj_to_python(getattr(obj, k)) for k in obj.__full_metadata_typed__ if hasattr(obj, k)}
-            )
+            return {k: cls._obj_to_python(getattr(obj, k)) for k in obj.__full_metadata_typed__ if hasattr(obj, k)}
         elif isinstance(obj, dict):
-            return {k: cls._obj_to_python(v) for k, v in obj.items()}
+            return type(obj)({k: cls._obj_to_python(v) for k, v in obj.items()})  # type() for derived dict types
         elif (
             isinstance(obj, (list, tuple, set)) or type(obj).__name__ == "FastList"
         ):  # hack for FastList that is not a list
@@ -126,10 +120,6 @@ def _obj_to_python(cls, obj):
         else:
             return obj
 
-    @classmethod
-    def _preprocess_dict_from_python(cls, d):
-        return d
-
     @classmethod
     def _obj_from_python(cls, json, obj_type):
         obj_type = ContainerTypeNormalizer.normalize_type(obj_type)
@@ -154,7 +144,6 @@ def _obj_from_python(cls, json, obj_type):
         elif issubclass(obj_type, Struct):
             if not isinstance(json, dict):
                 raise TypeError("Representation of struct as json is expected to be of dict type")
-            json = obj_type._preprocess_dict_from_python(json)
             res = obj_type()
             for k, v in json.items():
                 expected_type = obj_type.__full_metadata_typed__.get(k, None)