Summary says it all. Steps to reproduce:
- Create a job
- Add a validating string parameter with arbitrary data
- Save the config
- From the "Manage Jenkins" page, reload the configuration from disk
- Go back to the job config and see that the validating string parameter is gone!
I discovered this trying to load configuration programmatically from xml. Initially I assumed there was some error in my xml, but alas the scenario fails even with brand-spanking-new-generated-by-the-plugin xml.