install maven in jenkins via groovy

command-line-execute.sh

# command line to execute.
java -jar jenkins-cli.jar -s  http://localhost:8080/ groovy install-maven-in-jenkins.groovy

install-maven-in-jenkins.groovy

// install maven 
// file: maven3.groovy

import jenkins.*
import jenkins.model.*
import hudson.*
import hudson.model.*
a=Jenkins.instance.getExtensionList(hudson.tasks.Maven.DescriptorImpl.class)[0];
b=(a.installations as List);
b.add(new hudson.tasks.Maven.MavenInstallation("MAVEN3", "/home/jenkins/apache-maven/apache-maven-3.2.3", []));
a.installations=b
a.save()