Apply suggestions from code review

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

Author: wgd3

src/a2a/server/apps/jsonrpc/jsonrpc_app.py

@@ -137,11 +137,7 @@ def build(self, request: Request) -> ServerCallContext:
             user = StarletteUserProxy(request.user)
             state['auth'] = request.auth
         state['headers'] = dict(request.headers)
-        extension_values = request.headers.getlist(HTTP_EXTENSION_HEADER)
-        if not extension_values:
-            extension_values = request.headers.getlist(
-                HTTP_EXTENSION_HEADER_DEPRECATED
-            )
+        extension_values = request.headers.getlist(HTTP_EXTENSION_HEADER) or request.headers.getlist(HTTP_EXTENSION_HEADER_DEPRECATED)
         return ServerCallContext(
             user=user,
             state=state,

src/a2a/server/request_handlers/grpc_handler.py

@@ -73,11 +73,7 @@ def build(self, context: grpc.aio.ServicerContext) -> ServerCallContext:
         state = {}
         with contextlib.suppress(Exception):
             state['grpc_context'] = context
-        extension_values = _get_metadata_value(context, HTTP_EXTENSION_HEADER)
-        if not extension_values:
-            extension_values = _get_metadata_value(
-                context, HTTP_EXTENSION_HEADER_DEPRECATED
-            )
+        extension_values = _get_metadata_value(context, HTTP_EXTENSION_HEADER) or _get_metadata_value(context, HTTP_EXTENSION_HEADER_DEPRECATED)
         return ServerCallContext(
             user=user,
             state=state,