Fix bug in instantiating backed model with keyword args

kiota_abstractions/store/backed_model.py

@@ -4,7 +4,7 @@
 # See License in the project root for license information.
 # ------------------------------------------------------------------------------
 
-from dataclasses import dataclass
+from dataclasses import dataclass, fields
 
 from .backing_store import BackingStore
 
@@ -18,22 +18,15 @@ class BackedModel:
 
     def __post_init__(self):
         self.backing_store.is_initialization_completed = True
+        for field in fields(self):
+            if field.name != "backing_store":
+                field_val = getattr(self, field.name)
+                if field_val is not field.default:
+                    self.backing_store.set(field.name, field_val)
 
     def __setattr__(self, prop, val):
         if prop == "backing_store":
             super().__setattr__(prop, val)
         else:
             self.backing_store.set(prop, val)
-
-    def __getattribute__(self, prop):
-        if prop == "backing_store":
-            return super().__getattribute__(prop)
-        if self.backing_store.get(prop) is not None:
-            return self.backing_store.get(prop)
-        try:
-            attr = super().__getattribute__(prop)
-            if callable(attr):  # methods such as serialize and get_field_deserializers
-                return attr
-            return None
-        except AttributeError:
-            return None
+            super().__setattr__(prop, self.backing_store.get(prop))