Create new Jenkins user using RoleBasedStrategy and Groovy script

CreateJenkinsUser.groovy

import hudson.model.*
import hudson.security.*
import hudson.tasks.Mailer
import com.michelin.cio.hudson.plugins.rolestrategy.*

/*
* This snippet is inspired from a StackOverflow question and answer.
* https://stackoverflow.com/questions/17716242/creating-user-in-jenkins-via-api
*/
  
def userId = args[0]
def role = args[2]
def password = args[3]
def email = args[4]
def instance = jenkins.model.Jenkins.instance
def existingUser = instance.securityRealm.allUsers.find {it.id == userId}

if (existingUser == null) {
    def user = instance.securityRealm.createAccount(userId, password)
    user.addProperty(new Mailer.UserProperty(email));

    def strategy = (RoleBasedAuthorizationStrategy) instance.getAuthorizationStrategy()
    // See doAssignRole method in here
    // https://github.com/jenkinsci/role-strategy-plugin/blob/master/src/main/java/com/michelin/cio/hudson/plugins/rolestrategy/RoleBasedAuthorizationStrategy.java
  	strategy.doAssignRole("globalRoles", "developers", userId)
    instance.setAuthorizationStrategy(strategy)
  	instance.save()
    println "saved!"
} 

Usage via Jenkins API:

$ curl -u "$JENKINS_USERNAME:$JENKINS_API_TOKEN" https://jenkins.example.org/scriptText -d "script=$(< CreateJenkinsUser.groovy)"