Today, if you set a job in a public Jenkins instance to run on each gerrit patch from the community, it might be used by malicious user to run un-authorized code or malicious code on the jenkins server.
(for e.g. sending a patch to 'rm -rf... ')
also, it might be the jenkins server can't handle load of multiple patches and you want to restrict the job for specific users only.
one of the ways of handling this is maintaining a whitelist of authors that can trigger a jenkins job (once they send a patch).
so i suggest that the gerrit trigger plugin will be able to check if the author of the specific commit that triggered the job, match a whitelist that will be in a file (can be in the git repo itself).
if the author doesn't exist, the job can abort/fail.