try this
2.11.1 is needed - no 2.11. 2.12 I think requires a newer core?
@@ -6,6 +6,6 @@ USER root
# Add the docker binary so running Docker commands from the master works nicely
RUN apk -U add docker
-RUN install-plugins.sh workflow-job:2.11 antisamy-markup-formatter matrix-auth blueocean:$BLUEOCEAN_VERSION
+RUN install-plugins.sh workflow-job:2.11.1 antisamy-markup-formatter matrix-auth blueocean:$BLUEOCEAN_VERSION
USER jenkins
