I just found out that the plugin changes characters within config.xml of jobs.
This took me some time to find out why valid jobs running on other Jenkins instances without any problems crashed. The diffrence were that on this instance the JobConfigHistory-Plugin was installed.
It's also not immediately apparent in the Jenkins UI that the jobs have been changed because they are cached.
But after a restart of Jenkins the UI shows the changed characters.
Steps to reproduce the problem:
Create a new Job (or use a alread existing) with UTF-8 chars inside and save it with this plugin enabled.
Job config.xml without JobConfigHistory-plugin installed:
(Jira dont let me save this issue with utf-8 chars inside so // // is were the chars are)
The same Jobs config.xml after saving with JobConfigHistory installed:
All chars are transformed to HTML representation( &#"UTF-8-Number"; ), but config.xml are UTF-8 encoded, so this will change the characters to something with different meaning.