@Restricted(NoExternalUse.class)
    @CheckForNull
    public String getExtensionSource(Configurator c) throws IOException {
        final Class e = c.getImplementedAPI();
        final String jar = Which.jarFile(e).getName();
        if (jar.startsWith("jenkins-core-")) { // core jar has version in name
            return "jenkins-core";
        }
        return jar.substring(0, jar.lastIndexOf('.'));
    }
Retrieve which plugin do provide this extension point, used in documentation.jelly

@return String representation of the extension source, usually artifactId.
plugin/src/main/java/io/jenkins/plugins/casc/ConfigurationAsCode.java