Edit: For those who have the same problem, I used
Minecraft.getMinecraft().getBlockColors().registerBlockColorHandler((state, access, pos, tintIndex) -> BiomeColorHelper.getFoliageColorAtPos(access, pos), myCustomBlockInstance);
I'm trying to make a block that is visually identical to leaves. I got it working well (including fast/fancy graphics) except for colorization based on biome; my block is completely gray both in my inventory and in the world. I know that I can customize color in 1.8 with getRenderColor and/or colorMultiplier, but those methods don't appear to work at all in 1.9. I've looked around in the source a bit, but I can't find anywhere that vanilla leaves are colorized, so I have no idea how to even start colorizing my leaves.
Currently my leaf block is a subclass of BlockLeaves, and its blockstate json points to the oak_leaves model. If you want to look at my code (which you shouldn't need to), it's on Github here.
So, how can I colorize my leaves?