The job-dsl-plugin still refers to the Mattermost plugin's old showCommitList() functionality.  This was replaced in Mattermost Plugin 2.0 with commitInfoChoice(), and referred to under JENKINS-39239.  Jobs built with the DSL plugin's helpers for the Mattermost plugin are unable to set commitInfoChoice().  I'm opening a pull request back to the DSL repo with a fix for this.