If the SCM-Commit-Message-Checker-Plugin is installed, the Jira plugin will provide its own commit message issue key validator. This can be configured right on the commit message validation config.

Validator config

The Jira Issue Key Validator checks each commit for valid issue keys. The issue keys must match the Jira plugin config. You may enable this validator only for a set of branches like master,develop,feature/*. Leave branches blank to validate every branch. All new commits which does not contain a valid issue key will be rejected by the SCM-Manager.

Example: If you set the project filters in your Jira plugin configuration to "SCM" only issue keys beginning with this project id will be valid.