Edit user in Jenkins via groovy script - jenkins

Question

I am wondering if I can change password, username, email in Jenkins user. Because I am able to create user via groovy script like this:
import hudson.model.*
def user = instance.securityRealm.createAccount(userId, password)
user.addProperty(new Mailer.UserProperty(email));
instance.save()
Jenkins interface allows me to manage user credentials, but script which allow to change password/email/username would be very helpfull. I didnt find examples.
I tried many times with script like this, but It didnt work
import hudson.model.*
User user = User.getAll().get(1)
user.setProperty(newPassword)

Answer 1

Here's a simple code that works :
import jenkins.model.*
import hudson.security.*
import hudson.tasks.Mailer
def env = System.getenv()
def jenkins = Jenkins.getInstance()
if(!(jenkins.getSecurityRealm() instanceof HudsonPrivateSecurityRealm))
jenkins.setSecurityRealm(new HudsonPrivateSecurityRealm(false))
if(!(jenkins.getAuthorizationStrategy() instanceof GlobalMatrixAuthorizationStrategy))
jenkins.setAuthorizationStrategy(new GlobalMatrixAuthorizationStrategy())
// update admin Jenkins user account
def user = jenkins.getSecurityRealm().getUser('admin')
email= 'jenkins-admin#gmail.com'
user.addProperty(new Mailer.UserProperty(email));

Answer 2

For Jenkins Jenkins 2.361.1, I have used such Jenkins groovy script to update user's password:
User.getById("userName",false).addProperty(hudson.security.HudsonPrivateSecurityRealm.Details.fromPlainPassword("new-password"));
You can also easily run it from bash script or similar, given $USERNAME and $PASSWORD are set:
echo "script=User.getById(\"$USERNAME\",false).addProperty(hudson.security.HudsonPrivateSecurityRealm.Details.fromPlainPassword(\"$PASSWORD\"));" | \
curl -d #- --user admin:access_token http://<ip>:8080/scriptText