Remove usages of protected variables/class from external libraries [azure-ai-ml] (Azure#39875)

* remove protected variables/class usage

* correct variable

* update changelog

Author: PratibhaShrivastav18

sdk/ml/azure-ai-ml/CHANGELOG.md

@@ -10,6 +10,9 @@
   - #39744 - Fixing a serialization issue in RecurrencePattern schedule.
   - Fix environment archiving and restore
 
+### Other Changes
+  - Removing use of protected methods/classes imported from external libraries.
+
 ## 1.25.0 (2025-02-11)
 
 ### Features Added

sdk/ml/azure-ai-ml/azure/ai/ml/dsl/_group_decorator.py

@@ -5,7 +5,7 @@
 # disable redefined-builtin to use globals/locals as argument name
 
 # Attribute on customized group class to mark a value type as a group of inputs/outputs.
-import _thread
+import threading
 import functools
 from typing import Any, Callable, Dict, List, Optional, Type, TypeVar, Union
 
@@ -271,7 +271,7 @@ def _recursive_repr(user_function: Any) -> Any:
 
             @functools.wraps(user_function)
             def wrapper(self: Any) -> Any:
-                key = id(self), _thread.get_ident()
+                key = id(self), threading.get_ident()
                 if key in repr_running:
                     return "..."
                 repr_running.add(key)

sdk/ml/azure-ai-ml/azure/ai/ml/entities/_autogen_entities/_model_base.py

@@ -24,7 +24,7 @@
 from azure.core.exceptions import DeserializationError
 from azure.core import CaseInsensitiveEnumMeta
 from azure.core.pipeline import PipelineResponse
-from azure.core.serialization import _Null
+from azure.core.serialization import NULL
 
 if sys.version_info >= (3, 9):
     from collections.abc import MutableMapping
@@ -145,7 +145,7 @@ def default(self, o):  # pylint: disable=too-many-return-statements
         try:
             return super(SdkJSONEncoder, self).default(o)
         except TypeError:
-            if isinstance(o, _Null):
+            if isinstance(o, type(NULL)):
                 return None
             if isinstance(o, decimal.Decimal):
                 return float(o)
@@ -581,7 +581,7 @@ def as_dict(self, *, exclude_readonly: bool = False) -> typing.Dict[str, typing.
 
     @staticmethod
     def _as_dict_value(v: typing.Any, exclude_readonly: bool = False) -> typing.Any:
-        if v is None or isinstance(v, _Null):
+        if v is None or isinstance(v, type(NULL)):
             return None
         if isinstance(v, (list, tuple, set)):
             return type(v)(Model._as_dict_value(x, exclude_readonly=exclude_readonly) for x in v)
@@ -754,7 +754,7 @@ def _deserialize_with_callable(
     value: typing.Any,
 ):
     try:
-        if value is None or isinstance(value, _Null):
+        if value is None or isinstance(value, type(NULL)):
             return None
         if deserializer is None:
             return value