I was in a hurry yesterday and I realize only now that I seemed a bit rude, that wasn't my intention, sorry.
I asked because I got the same error message after installing bitbucket-plugin (which has git-plugin as dependency along with many other) on both latest and latest stable release of Jenkins, although using the jenkins.war on tomcat with java 16 which I know is not supported.
So I was just hoping this could lead to solving the issues even for my case.
I managed to use jenkins (latest stable) in tomcat 9 with java 16 till with those 2 plugins till 2 days ago, when I upgraded tomcat to version 10 and had to use their tool to migrate .war files for their newer version. It started, but gave me the same error message after installing those plugins.
Anyway considering I'm using not supported software I won't have any word on this. and anyway Mark you have a good point I won't wrestle with anything, that wasn't my intention I was merely curious but I realize I didn't use the best approach
I'll see if I can test all of this with a supported java version