The concurrency exception addressed in 1.12.x has reappeared.
- dev_summer branch
- create Presenter
- click 'Create' (the contributed action to propose a session)
- in the resultant Session, click on the "Other" tab (where the Presenter reference lives)
- bam, concurrency exception.
Suggest the fix instead is to postpone the EntityPage#buildGui into the onRender, so that reload all objects on the redirect. Have considered this in the past but had been able to make it work without resorting to this.