For some branches in certain repos, we would like to be able to make backport records with a different security level than the main bug. To do this, we need a branch level configuration option for setting a custom default security level in the issue notifier. The branch names need to be patterns, so we can easily define a static configuration that doesn't need updating for new branches. I think something like this would do it:

       "issue": {
          "project": "bugs/JDK",
          "fixversions": {},
          "buildname": "master",
          "headversion": true,
          "defaultsecurity": { // <- new
            "jdk.*": "10000",
          }
        },

The security field defines a default level that should match a level definition in Jira. If the main bug already has a security level set, then that should be used, but if it doesn't, then this default level would be picked up.