chore: change LlmRequest.config's default value to be types.GenerateContentConfig() instead of None

PiperOrigin-RevId: 789792582

tests/unittests/tools/test_base_tool.py

@@ -62,7 +62,7 @@ async def test_process_llm_request_no_declaration():
       tool_context=tool_context, llm_request=llm_request
   )
 
-  assert llm_request.config is None
+  assert llm_request.config == types.GenerateContentConfig()
 
 
 @pytest.mark.asyncio

tests/unittests/tools/test_google_search_tool.py

@@ -322,12 +322,12 @@ class TestGoogleSearchTool:
       )
 
   @pytest.mark.asyncio
-  async def test_process_llm_request_with_none_config(self):
+  async def test_process_llm_request_with_no_config(self):
     """Test processing LLM request with None config."""
     tool = GoogleSearchTool()
     tool_context = await _create_tool_context()
 
-    llm_request = LlmRequest(model='gemini-2.0-flash', config=None)
+    llm_request = LlmRequest(model='gemini-2.0-flash')
 
     await tool.process_llm_request(
         tool_context=tool_context, llm_request=llm_request

tests/unittests/tools/test_url_context_tool.py

@@ -242,12 +242,12 @@ class TestUrlContextTool:
       )
 
   @pytest.mark.asyncio
-  async def test_process_llm_request_with_none_config(self):
+  async def test_process_llm_request_with_no_config(self):
     """Test processing LLM request with None config."""
     tool = UrlContextTool()
     tool_context = await _create_tool_context()
 
-    llm_request = LlmRequest(model='gemini-2.0-flash', config=None)
+    llm_request = LlmRequest(model='gemini-2.0-flash')
 
     await tool.process_llm_request(
         tool_context=tool_context, llm_request=llm_request