Minecraft forge 1.9 problem?

I'm updating my mod to 1.9 today, but i've soon noticed an issue with fluids. They are considered as solid blocks, therefore i can't "dive" in them, i can literaly walk on water.

The vanilla fluid block override the method AxisAlignedBB, which if I'm right, also controls the collision box. Override that to return null should fix it.

Every time i join a game it kick me out to the minecraft launcher