Using gradle plugins offline

I have a setup where I am using my own Artifactory to where I keep dependencies for my project. This works fine. However this morning https://plugins.gradle.com was down, and I was surprised to see my builds failing. Looking into it it was coming from one of the few ajoberstar (Andrew Oberstar) · GitHub plugins that I use:

10:36:53 A problem occurred configuring root project ‘foo-bar’.
10:36:53 > Could not resolve all artifacts for configuration ‘:classpath’.
10:36:53 > Could not resolve org.eclipse.jgit:org.eclipse.jgit:[5.0,6.0).
10:36:53 Required by:
10:36:53 project : > org.ajoberstar.reckon:reckon-gradle:0.12.0
10:36:53 > Failed to list versions for org.eclipse.jgit:org.eclipse.jgit.
10:36:53 > Unable to load Maven meta-data from JFrog.
10:36:53 > Could not get resource ‘JFrog’.
10:36:53 > Could not GET ‘https://jcenter.bintray.com/org/eclipse/jgit/org.eclipse.jgit/maven-metadata.xml’. Received status code 502 from server: Bad Gateway

My build machines are virtual machines which are discarded after each use, so using --offline is not an option for me. Is there a way I can address this and keep my builds running even when gradle domain or jcenter/bintray is down?