[Bug fixes] update attribute map handler (#4421)

* update config

* update legacy config

* add comment for change

* trigger cla

paddlenlp/transformers/configuration_utils.py

@@ -195,8 +195,12 @@ def convert_to_legacy_config(attribute_map: Dict[str, str], config: Dict[str, An
             args.append(init_arg)
         config["init_args"] = args
 
+    # TODO(wj-Mcat): to improve compatibility for: old local config and new PretrainedConfig, eg:
+    # { "init_args": [], "init_class": "", "num_classes": 12 }
     for standard_field, paddle_field in attribute_map.items():
-        config[paddle_field] = config.pop(standard_field, None) or config.pop(paddle_field, None)
+        value = config.pop(standard_field, None) or config.pop(paddle_field, None)
+        if value is not None:
+            config[paddle_field] = value
     return config
 
 
@@ -729,16 +733,6 @@ def from_pretrained(
 
         config_dict, kwargs = cls.get_config_dict(pretrained_model_name_or_path, **kwargs)
 
-        # do standard config map: there are some old-school pretrained-config not refactored.
-        config_dict = convert_to_legacy_config(cls.attribute_map, config_dict)
-
-        config_dict = flatten_model_config(config_dict)
-        if "model_type" in config_dict and hasattr(cls, "model_type") and config_dict["model_type"] != cls.model_type:
-            logger.warning(
-                f"You are using a model of type {config_dict['model_type']} to instantiate a model of type "
-                f"{cls.model_type}. This is not supported for all configurations of models and can yield errors."
-            )
-
         return cls.from_dict(config_dict, **kwargs)
 
     @classmethod
@@ -859,12 +853,18 @@ def from_dict(cls, config_dict: Dict[str, Any], **kwargs) -> "PretrainedConfig":
             [`PretrainedConfig`]: The configuration object instantiated from those parameters.
         """
         return_unused_kwargs = kwargs.pop("return_unused_kwargs", False)
-        # Those arguments may be passed along for our internal telemetry.
-        # We remove them so they don't appear in `return_unused_kwargs`.
 
-        # convert local config to legacy config
+        # do standard config map: there are some old-school pretrained-config not refactored.
         config_dict = convert_to_legacy_config(cls.attribute_map, config_dict)
 
+        config_dict = flatten_model_config(config_dict)
+
+        if "model_type" in config_dict and hasattr(cls, "model_type") and config_dict["model_type"] != cls.model_type:
+            logger.warning(
+                f"You are using a model of type {config_dict['model_type']} to instantiate a model of type "
+                f"{cls.model_type}. This is not supported for all configurations of models and can yield errors."
+            )
+
         config = cls(**config_dict)
 
         if hasattr(config, "pruned_heads"):