This is now done by the metadata implementation.
Doing this manually causes assertion failures, because then the
target.node is removed before policy-node "unhandles" the associated
session item and it tries to re-link it to the default source/sink
Make a module that creates a route-settings metadata and provides
some helper functions to parse the json fields.
Load the route-settings module in the policy.
Move the Notification settings to the metadata. Listen for metadata
updates and update our state table.
Fixes#51
