Jenkins groovy configuration

jenkins_config.groovy

def projects = [:];

projects['first-repo'] = [
  name: 'First multibranch pipeline',
  repo: 'repo-first'
]

projects['second-repo'] = [
  name: 'Second multibranch pipeline',
  repo: 'repo-second'
]


projects.each { id, project ->
  multibranchPipelineJob(id) {
      displayName(project.name)
      description("Do not change this configuration manually!")
      branchSources {
          branchSource {
              source {
                  bitbucket {
                      serverUrl("https://url-of-the-server")
                      repoOwner('NAME-OF-OWNER')
                      repository(project.repo)
                      credentialsId('LOOOOONG-ID-ID-ID-ID')
                  }
              }
          }

          // check every minute for scm changes as well as new / deleted branches
          triggers {
              periodic(1)
          }

          // don't keep build jobs for deleted branches
          orphanedItemStrategy {
              discardOldItems {
                  numToKeep(-1)
              }
          }
      }

      configure {
          def traits = it / sources / data / 'jenkins.branch.BranchSource' / source / traits

          traits << 'com.cloudbees.jenkins.plugins.bitbucket.TagDiscoveryTrait' {
              strategyId(3)
          }

          traits << 'jenkins.branch.buildstrategies.basic.TagBuildStrategyImpl' { // <<<<< this doesn't work
              strategyId(1)
          }

          it / factory(class: 'org.jenkinsci.plugins.workflow.multibranch.WorkflowBranchProjectFactory') {
              owner(class: 'org.jenkinsci.plugins.workflow.multibranch.WorkflowMultiBranchProject', reference: '../..')
              scriptPath('Jenkinsfile')
          }
      }
  }
}