dockerhub-notification plugin job config breaks with form changes

Context:  testing the drag & drop with the new form layout (https://github.com/jenkinsci/jenkins/pull/3895)

I have found that the freestyle job configuration of the  dockerhub-notification-plugin (https://github.com/jenkinsci/dockerhub-notification-plugin) is not working correctly with the new form changes.

It redefines several Jenkins Core widgets such as f:optionalBlock and f:expandableTextbox, and they stop working.

Submitting the form does not save the configuration.

Before: dockerhubplugin-pre.mov

Wrong behaviour: dockerhubnotification-post.mov