Axolotls and Glow Squids can spawn in Mushroom fields biome

I'm not sure if this is intended to work as such, but Glow Squids and Axolotls can spawn on Mushroom Fields biome(s) given the appropriate conditions.

1. Start a Superflat world of a Mushroom fields biome with at least 2 layers of water (below sea level) and a layer of a random block above them. Example: minecraft:bedrock,2*minecraft:dirt,2*minecraft:water,30*minecraft:air,minecraft:glass;minecraft:mushroom_fields

2. Notice that Glow Squids and Axolotls can spawn inside the water.