fix: pass modifier to handler

Author: kthota-g

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

@@ -64,6 +64,7 @@ def add_routes_to_app(
 
         if agent_card_url == AGENT_CARD_WELL_KNOWN_PATH:
             # For backward compatibility, serve the agent card at the deprecated path as well.
+            # TODO: remove in a future release
             app.get(PREV_AGENT_CARD_WELL_KNOWN_PATH)(
                 self._handle_get_agent_card
             )

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

@@ -160,6 +160,7 @@ def __init__(  # noqa: PLR0913
             agent_card=agent_card,
             request_handler=http_handler,
             extended_agent_card=extended_agent_card,
+            extended_card_modifier=extended_card_modifier,
         )
         if (
             self.agent_card.supports_authenticated_extended_card

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

@@ -59,6 +59,8 @@ def routes(
         ]
 
         if agent_card_url == AGENT_CARD_WELL_KNOWN_PATH:
+            # For backward compatibility, serve the agent card at the deprecated path as well.
+            # TODO: remove in a future release
             app_routes.append(
                 Route(
                     PREV_AGENT_CARD_WELL_KNOWN_PATH,