setupDecompWorkspace does not exist in ForgeGradle 3, that work is now done when the IDE imports/refreshes the project.
I believe I heard this is an issue with intellij not liking tasks that are added dynamically or something.
You first asked for help with 1.7.10 and upon being told we don't support that version you spammed DMs to me repeatedly asking for help with 1.7.10 anyway.
Now you're prioritizing pleaing for help over providing the information you have been asked for.... information that we need in order to help you.
Continue this behavior and you shouldn't be surprised when you receive more warning points continuing to increase towards the ban threshold.