chore: Add LiteLLM streaming sample

Co-authored-by: George Weale <gweale@google.com>
PiperOrigin-RevId: 869397634

contributing/samples/litellm_streaming/agent.py

@@ -0,0 +1,27 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""LiteLLM sample agent for SSE text streaming."""
+
+from __future__ import annotations
+
+from google.adk import Agent
+from google.adk.models.lite_llm import LiteLlm
+
+root_agent = Agent(
+    name='litellm_streaming_agent',
+    model=LiteLlm(model='gemini/gemini-2.5-flash'),
+    description='A LiteLLM agent used for streaming text responses.',
+    instruction='You are a verbose assistant',
+)