Setup forge-build with shadow and as subproject?

[TBlueF]

Hello guys

So i am working on a bigger plugin/mod currently that i want to be compatible with multiple API's like Bukkit, Sponge and now Forge.
This is currently built with gradle and the johnrengelman.shadow plugin to make an universal jar. Here is the project.

With the last commit in that branch i tried to add the Forge Implementation but when i am trying to build it i get this issue that i don't know how to fix:

> Configure project :BlueMapForge
New Dep: net.minecraftforge:forge:1.14.4-28.1.0_mapped_stable_58

FAILURE: Build failed with an exception.

* What went wrong:
Could not determine the dependencies of task ':shadowJar'.
> Could not resolve all dependencies for configuration ':runtimeClasspath'.
   > Could not find net.minecraftforge:forge:1.14.4-28.1.0_mapped_stable_58.
...

Here is the full error and gradle scan: https://gradle.com/s/7z2is226v6v3q

I am currently using gradle 5.6.4 with this built but i have also tried gradle 4.9 which gets me exactly the same error ^^

[TBlueF]

So if no one knows this, does somebody has an idea where i might get more help with this issue?
Or do you think this is just not feasible like this?

[LexManos]

You should not be shading all of minecraft/its dependencies into your jar file...

You could in theory make a single jar that works on all systems if you keep everything abstracted out.

But honestly it's better/easier to just build separate jars.

[TBlueF]

No, you misunderstood @LexManos 
I don't want to shade forge or minecraft, i am shading only libs that i am using myself ... i want to exclude forge/minecraft from the shading like i already do with bukkit and sponge.
I just want forge to compile with it, while using the shade-plugin and having the forge implementation/dependency in a gradle sub-project. 
Dynmap does the same thing, but i can't get it to work for my project.