You should make a game editor. So far there is no real platform for game developers in java.
Maybe a GLSL designer, Pipeline over-view, Level editor, stuff like that.
The only other editor is JMonkey engine. But that doesn't really let you make your own engine. (Handle textures in specific way and all)
Uh, but's what a game engine is, no?
jMonkeyEngine: make your game
You want lower level, more control? libGDX. It's a framework, not an engine. You build your engine, and then your game.
Lower than that? LWJGL. You build (nearly) everything.
Also for GLSL there's shadertoy (limited, but good for fragment shader testing), and then there's SynthEclipse
Level editor? Gonna pretty much be game-specific. There's also Tiled.
Not sure what you mean by pipeline overview.