set private attributes with PrivateAttr instead of config

libs/community/langchain_google_community/vertex_ai_search.py

@@ -20,7 +20,7 @@
 from langchain_core.retrievers import BaseRetriever
 from langchain_core.tools import BaseTool
 from langchain_core.utils import get_from_dict_or_env
-from pydantic import ConfigDict, Field, model_validator
+from pydantic import ConfigDict, Field, PrivateAttr, model_validator
 
 from langchain_google_community._utils import get_client_info
 
@@ -256,13 +256,12 @@ class VertexAISearchRetriever(BaseRetriever, _BaseVertexAISearchRetriever):
     https://cloud.google.com/generative-ai-app-builder/docs/reference/rest/v1beta/BoostSpec
     """
 
-    _client: SearchServiceClient
-    _serving_config: str
+    _client: SearchServiceClient = PrivateAttr()
+    _serving_config: str = PrivateAttr()
 
     model_config = ConfigDict(
         extra="forbid",
         arbitrary_types_allowed=True,
-        underscore_attrs_are_private=True,
     )
 
     def __init__(self, **kwargs: Any) -> None:
@@ -418,13 +417,12 @@ class VertexAIMultiTurnSearchRetriever(BaseRetriever, _BaseVertexAISearchRetriev
     conversation_id: str = "-"
     """Vertex AI Search Conversation ID."""
 
-    _client: ConversationalSearchServiceClient
-    _serving_config: str
+    _client: ConversationalSearchServiceClient = PrivateAttr()
+    _serving_config: str = PrivateAttr()
 
     model_config = ConfigDict(
         extra="ignore",
         arbitrary_types_allowed=True,
-        underscore_attrs_are_private=True,
     )
 
     def __init__(self, **kwargs: Any):
@@ -501,10 +499,10 @@ class VertexAISearchSummaryTool(BaseTool, VertexAISearchRetriever):
     summary_spec_kwargs: Dict[str, Any] = Field(default_factory=dict)
     """ Additional kwargs for `SearchRequest.ContentSearchSpec.SummarySpec`"""
 
-    class Config(VertexAISearchRetriever.Config):
-        """Redefinition to specify that inherits config from `VertexAISearchRetriever`
-        not BaseTool
-        """
+    model_config = ConfigDict(
+        extra="forbid",
+        arbitrary_types_allowed=True,
+    )
 
     def _get_content_spec_kwargs(self) -> Optional[Dict[str, Any]]:
         """Adds additional summary_spec parameters to the configuration of the search.