Configure Maven installations in Jenkins using a post-initialization script (https://wiki.jenkins.io/display/JENKINS/Post-initialization+script)

addMavenInstallations.groovy

import hudson.tasks.Maven.MavenInstallation
import hudson.tasks.Maven.MavenInstaller
import hudson.tools.InstallSourceProperty

/*
 * add Maven installations to global tool configrations
 */

hudson.tasks.Maven.DescriptorImpl mavenPlugin = Jenkins.instance.getExtensionList(hudson.tasks.Maven.DescriptorImpl).first()
mavenPlugin.installations = [
    new MavenInstallation('3.6.0', null, [new InstallSourceProperty([new MavenInstaller('3.6.0')])]),
    new MavenInstallation('3.2.5', null, [new InstallSourceProperty([new MavenInstaller('3.2.5')])]),
    new MavenInstallation('3.1.1', null, [new InstallSourceProperty([new MavenInstaller('3.1.1')])])
]

Jenkinsfile

pipeline {

    agent any

    tools {
        maven "3.2.5"
    }

    stages {
        stage("Use maven") {
            steps {
                sh "mvn --version"
            }
        }
    }
}