Transitional biome between gravelly mountains and ocean is not stone beach

The transitional biome between gravelly mountains and ocean is a regular beach instead of stone beach. 

To replicate: find a gravelly mountain biome that's generated next to any ocean type. Observe the boundary between the gravelly mountains and where it touches water.

Seed I used: -698574988039417727
Coordinates: x = 500, y = 100, z = -1700