Based on your comments, you could redesign your process. My approach would be:
You could publish a webservice in Mendix and call this one from your JMS connector. See documentation how to publish a webservice with a microflow.
Basically you need to model all entities in a domain model and select the main entity in your published webservice microflow. Then you can configure which attributes/associations are available in the webservice. You need to map the temporary objects in your microflow to real objects in your domain model. After that, call the webservice in your jms connection.
This way you don't need any FileDocument.