ADK changes

PiperOrigin-RevId: 799760971

Author: hangfei

contributing/samples/hello_world/agent.py

@@ -17,7 +17,7 @@
 from google.adk import Agent
 from google.adk.tools.tool_context import ToolContext
 from google.genai import types
-
+from google.adk.apps import App
 
 def roll_die(sides: int, tool_context: ToolContext) -> int:
   """Roll a die and return the rolled result.
@@ -106,3 +106,12 @@ async def check_prime(nums: list[int]) -> str:
         ]
     ),
 )
+
+# The name "app" need to be exactly the same so ADK app loader can locate it and load it.
+app = App(
+    name='hello_world_app',
+    root_agent=root_agent,
+    plugins=[
+        SamplePlugin(),
+    ],
+)