To replicate:

1. Open the in-product REST API Browser at /plugins/servlet/restbrowser#/
2. Click on the link called "Bamboo REST API tutorials" (screenshot attached)
3. A DAC page appears saying "The license could not be verified: License Certificate has expired!" (screenshot also attached)

I'm running Bamboo from JBAM using atlas-run --product bamboo, so it's possible this is only a dev-time problem relating to the Bamboo license. However, there are a couple of comments on the DAC page complaining about it being broken, so it might be an actual problem.