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

Author: holtskinner

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

@@ -170,35 +170,8 @@ class JSONRPCApplication(ABC):
         | GetAuthenticatedExtendedCardRequest
     )
 
-    # Pydantic model fields like 'method' are instance attributes, not class attributes.
-    # So, 'Type.method' does not exist until you instantiate the model.
-    # To get the default value for the 'method' field at the class level,
-    # you must use Type.model_fields["method"].default.
-    METHOD_TO_MODEL: dict[str, type[A2ARequestModel]] = {
-        SendMessageRequest.model_fields['method'].default: SendMessageRequest,
-        SendStreamingMessageRequest.model_fields[
-            'method'
-        ].default: SendStreamingMessageRequest,
-        GetTaskRequest.model_fields['method'].default: GetTaskRequest,
-        CancelTaskRequest.model_fields['method'].default: CancelTaskRequest,
-        SetTaskPushNotificationConfigRequest.model_fields[
-            'method'
-        ].default: SetTaskPushNotificationConfigRequest,
-        GetTaskPushNotificationConfigRequest.model_fields[
-            'method'
-        ].default: GetTaskPushNotificationConfigRequest,
-        ListTaskPushNotificationConfigRequest.model_fields[
-            'method'
-        ].default: ListTaskPushNotificationConfigRequest,
-        DeleteTaskPushNotificationConfigRequest.model_fields[
-            'method'
-        ].default: DeleteTaskPushNotificationConfigRequest,
-        TaskResubscriptionRequest.model_fields[
-            'method'
-        ].default: TaskResubscriptionRequest,
-        GetAuthenticatedExtendedCardRequest.model_fields[
-            'method'
-        ].default: GetAuthenticatedExtendedCardRequest,
+    METHOD_TO_MODEL = {
+        model.model_fields["method"].default: model for model in A2ARequestModel.__args__
     }
 
     def __init__(  # noqa: PLR0913