fix: converts litellm generate config err

Merge https://github.com/google/adk-python/pull/1509

Fixs: #1302

Previous PR: https://github.com/google/adk-python/pull/1450

COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/1509 from simonwei97:fix/litellm-gen-config-converting-err 3120887f29a21789f1b4a7c54af3ed35eb5055e3
PiperOrigin-RevId: 775903671

tests/unittests/models/test_litellm.py

@@ -1447,3 +1447,35 @@ async def test_generate_content_async_non_compliant_multiple_function_calls(
   assert final_response.content.parts[1].function_call.name == "function_2"
   assert final_response.content.parts[1].function_call.id == "1"
   assert final_response.content.parts[1].function_call.args == {"arg": "value2"}
+
+
+@pytest.mark.asyncio
+def test_get_completion_inputs_generation_params():
+  # Test that generation_params are extracted and mapped correctly
+  req = LlmRequest(
+      contents=[
+          types.Content(role="user", parts=[types.Part.from_text(text="hi")]),
+      ],
+      config=types.GenerateContentConfig(
+          temperature=0.33,
+          max_output_tokens=123,
+          top_p=0.88,
+          top_k=7,
+          stop_sequences=["foo", "bar"],
+          presence_penalty=0.1,
+          frequency_penalty=0.2,
+      ),
+  )
+  from google.adk.models.lite_llm import _get_completion_inputs
+
+  _, _, _, generation_params = _get_completion_inputs(req)
+  assert generation_params["temperature"] == 0.33
+  assert generation_params["max_completion_tokens"] == 123
+  assert generation_params["top_p"] == 0.88
+  assert generation_params["top_k"] == 7
+  assert generation_params["stop"] == ["foo", "bar"]
+  assert generation_params["presence_penalty"] == 0.1
+  assert generation_params["frequency_penalty"] == 0.2
+  # Should not include max_output_tokens
+  assert "max_output_tokens" not in generation_params
+  assert "stop_sequences" not in generation_params