（求解）关于构建MC水影客户端的一个问题

最近下载了一个我的世界1.12.2水影客户端的码子
使用IDEA打开
但是当我构建（gradle）时出现了一个错误：

problem occurred configuring project ':1.12.2-Forge'.
> Could not resolve all artifacts for configuration ':1.12.2-Forge:classpath'.
   > Could not find mixingradle.jar (org.spongepowered:mixingradle:0.6-SNAPSHOT).
     Searched in the following locations:
         https://files.minecraftforge.net/maven/org/spongepowered/mixingradle/0.6-SNAPSHOT/mixingradle-0.6-SNAPSHOT.jar

Possible solution:
 - Declare repository providing the artifact, see the documentation at https://docs.gradle.org/current/userguide/declaring_repositories.html


其中提到的链接：https://files.minecraftforge.net/maven/org/spongepowered/mixingradle/0.6-SNAPSHOT/mixingradle-0.6-SNAPSHOT.jar我打开看了一下，但是显示的是404 NotFound
本人小白刚开始学习一直解决不了，上网看了很多教程也搞不明白，请指点一下谢谢！！！