Jenkinsfile: Send mail to all users listed in "People"

Question

I would like to send an e-mail notification to all users listed in the People tab in the job view:

The post Use Jenkins 'Mailer' inside pipeline workflow shows how to send e-mail notifications within a Jenkinsfile:

emailext(body: '${DEFAULT_CONTENT}', mimeType: 'text/html',
         replyTo: '$DEFAULT_REPLYTO', subject: '${DEFAULT_SUBJECT}',
         to: emailextrecipients([[$class: 'CulpritsRecipientProvider'],
                                 [$class: 'RequesterRecipientProvider']]))

I modified it to send e-mails only if the build failed or fixed, inspired by Justin Simons comment in https://baptiste-wicht.com/posts/2017/06/jenkins-tip-send-notifications-fixed-builds-declarative-pipeline.html#comment-3478592834:

mailNotificationAlreadySend = false

pipeline {

    ...

    stages {
    ...
    }

    post {
        changed {
            sendMailNotification()
        }
        failure {
            sendMailNotification()
        }
    }
}

void sendMailNotification() {

    if (!mailNotificationAlreadySend) {

        emailext(body: '${DEFAULT_CONTENT}', mimeType: 'text/html',
                replyTo: '$DEFAULT_REPLYTO', subject: '${DEFAULT_SUBJECT}',
                recipientProviders: [[$class: 'DevelopersRecipientProvider'],
                                     [$class: 'CulpritsRecipientProvider']]
        )

        mailNotificationAlreadySend = true
    }
}

But this sends the e-mails only to the developer who caused the build fail and all following contributors until the build result is successful again.

How should the emailext method be configured to send e-mails to all users listed in the People tab in the job view?

I already tried all recipientProviders available in https://github.com/jenkinsci/email-ext-plugin/tree/master/src/main/java/hudson/plugins/emailext/plugins/recipients without any success.