Forge Workspace Setup
Obtaining the MDK
The official Forge MDK (Modding Development Kit) is available at Forge's website. However, MDKs for legacy versions no longer function out of the box. Therefore it's recommended to start from one of the following modern template projects instead.
(For the curious, a guide to fixing up the old build script can be found here)
Template projects
For more info about each Gradle plugin, refer to Gradle Plugins.