Instructions in Readme.md on how to include HF are incorrect.
I ran ./gradlew --refresh-dependencies -Dorg.gradle.jvmargs=-Xmx2G setupDecompWorkspace
This is the console log.
And this is my build.gradle.

Yup, just like TehNut said :)

Wrong repositories block. You put it in the Buildscript repositories, not the project repositories. The README instructions are correct.