install_plugin_via_groovy

pluginShortName = "jabber"
Jenkins.instance.updateCenter.getPlugin(pluginShortName).getNeededDependencies().each {
    it.deploy()
}

updateCenterJob = Jenkins.instance.updateCenter.getPlugin(pluginShortName).deploy()

if (Jenkins.instance.updateCenter.isRestartRequiredForCompletion()) {
    hudson.model.Hudson.instance.doSafeRestart(null)
}