gradle.org is down at the moment (getting CloudFlare 522 error). One of the services CloudFlare offers is caching yet CloudFlare is saying
Website is offline No cached version of this page is available.
I strongly recommend going into CloudFlare and setting up caching on all static files, which includes the gradle distributions and the docs. At the moment, I am unable to build my project because of this outage and the only thing necessary to prevent this sort of outage of the static docs pages and the distribution files is spending a bit of time and configuring CloudFlare to do caching (especially during outages).