I think working version now, testing

src/transformers/training_args.py

@@ -1131,7 +1131,7 @@ class TrainingArguments:
         },
     )
     fsdp_config: Optional[Union[dict, str]] = field(
-        default_factory=dict,
+        default=None,
         metadata={
             "help": (
                 "Config to be used with FSDP (Pytorch Fully Sharded  Data Parallel). The value is either a "
@@ -1149,7 +1149,7 @@ class TrainingArguments:
         },
     )
     accelerator_config: Optional[Union[AcceleratorConfig, dict, str]] = field(
-        default_factory=dict,
+        default=None,
         metadata={
             "help": (
                 "Config to be used with the internal Accelerator object initializtion. The value is either a "
@@ -1158,7 +1158,7 @@ class TrainingArguments:
         },
     )
     deepspeed: Optional[Union[dict, str]] = field(
-        default_factory=dict,
+        default=None,
         metadata={
             "help": (
                 "Enable deepspeed and pass the path to deepspeed json config file (e.g. `ds_config.json`) or an already"
@@ -1262,7 +1262,7 @@ class TrainingArguments:
         },
     )
     gradient_checkpointing_kwargs: Optional[Union[dict, str]] = field(
-        default_factory=dict,
+        default=None,
         metadata={
             "help": "Gradient checkpointing key word arguments such as `use_reentrant`. Will be passed to `torch.utils.checkpoint.checkpoint` through `model.gradient_checkpointing_enable`."
         },
@@ -1391,10 +1391,15 @@ class TrainingArguments:
     def __post_init__(self):
         # Parse in args that could be `dict` sent in from the CLI as a string
         for field in VALID_DICT_FIELDS:
+            passed_value = getattr(self, field)
             # We only want to do this if the str starts with a bracket to indiciate a `dict`
             # else its likely a filename if supported
-            if isinstance(getattr(self, field), str) and getattr(self, field).startswith("{"):
-                setattr(self, field, json.loads(getattr(self, field)))
+            if isinstance(passed_value, str) and passed_value.startswith("{"):
+                setattr(self, field, json.loads(passed_value))
+            # Since we default to a blank dict, set it to `None` after parsing
+            elif isinstance(passed_value, dict):
+                if passed_value == {}:
+                    setattr(self, field, None)
 
         # expand paths, if not os.makedirs("~/bar") will make directory
         # in the current directory instead of the actual home