[1.8]Rendering snowball like entity

In 1.7 to render my grenade entity like the snowball in the client proxy register renders method i just did this.

RenderingRegistry.registerEntityRenderingHandler(EntityGrenade.class, new RenderSnowball(BioWarfare.itemGrenade));

but in 1.8 now there are two extra arguments and i'm not sure what they represent and when i set them to null it crashes.

my 1.8 code that crashes:

RenderingRegistry.registerEntityRenderingHandler(EntityGrenade.class, new RenderSnowball(null, BioWarfare.itemGrenade,null) );