As discussed on Mattermost with @jesse, the JMS Northbounder's configuration for <send-as-object-message>true</send-as-object-message> doesn't actually work, because the object is not marked as Serializable.

Spring defaults to using SimpleMessageConverter, but can be configured to use MappingJackson2MessageConverter instead (which turns everything into JSON with Jackson).

Since the existing feature does not work, it's probably best to just drop the <send-as-object-message> option entirely, and replace it with <send-as-json>true</send-as-json, which uses the Jackson message converter.