I got into minecraft modding recently and was surprised by how hard it is to find useful up-to-date information. Because of that, I decided to document my learning journey and write a book about Minecraft modding for beginners. It applies to Minecraft 1.16.1 and the latest version of forge.
Keep in mind it is still a work in progress. More chapters will be added in the coming days. Suggestions and questions also are welcomed.
Link: https://thebookofmodding.ml/
I'd say 1.15.2 is the best to look into the source code for. After all, it's resent, and it's fairly complete in terms of mappings. Next, 1.12.2 has everything mapped, but it's old.
Don't tell ppl "do your research before posting here" as the README.txt file that comes with the MDK of Forge 1.13.2 25.0.9 and 25.0.10 says to use setupDecomWorkspace its obvious that the README.txt file was not updated but you don't have to be a dick.
'setupDecompWorkspace' no longer exists. Forge, and by extent ForgeGradle, for 1.13.x received major rewrites, and a lot of things are done very differently. Please do your research before posting here.
Also, Java 11 is not supported. Use Java 8, 9 or 10.