Issue description:

The API jar files for building projects that depend on RS are unavaliable, which leads to the issue that such projects can't be built anymore.

What happens:

Currently trying to build Building Gadgets for 1.12, which depends on refinedstorage:refinedstorage:1.6.15-380.
Gradle tries to contact following sources but can't find anything:
https://gist.github.com/4rz0/55757c9b6863188ee95d2d30b613d86b

Version (make sure you are on the latest version before reporting):

• Minecraft: 1.12
• Forge: 1.12.2 - 14.23.5.2854
• Refined Storage: refinedstorage:refinedstorage:1.6.15-380

Does this issue occur on a server? [yes/no]

#### If a (crash)log is relevant for this issue, link it here:

[pastebin/gist/etc link here]

Use the search function on the issue tracker

#2724, for those who found this one before the original post.