RecipientProviders in Jenkins pipe are always empty

Question

after finishing work, I want to send an email notification. If the task is started manually at least RequesterRecipientProvider, if it is filled by the user who called the assembly. I called push webhook from gitlab, there is no email address configured for any of the recipient providers.

    emailext (
      mimeType: 'text/html',
      replyTo: '$DEFAULT_REPLYTO', 
      subject: subject,
      body: details,
      to: requester,
      recipientProviders: [[$class: 'CulpritsRecipientProvider'],
                         [$class: 'RequesterRecipientProvider'],
                         [$class: 'DevelopersRecipientProvider'],
                         [$class: 'FailingTestSuspectsRecipientProvider'             ], 
                         [$class: 'FirstFailingBuildSuspectsRecipientProvider']
                        ]
        )

Any idea when those recipient Provider populate? Where does email-ext get the list of recipients?