Buffet Floating Islands worlds generate dirt instead of grass

The bug

In the Minecraft snapshot 18w46a, Buffet worlds now generate the Floating Islands generator type differently. When the biome in question is one which has surface grass (e.g. Forest, Jungle, etc.), only very few blocks of grass generate on the surface around the player's spawn point, and the rest of the surface is covered in dirt instead.

Previous snapshots generated every dirt block exposed to the surface and appropriate sunlight as a grass block instead.

How to reproduce

Just create a Buffet Floating Islands world with a biome that has surface grass. I tested this with Jungle Hills, Jungle, and Forest.