craftbukkit/nms-patches/net/minecraft/world/level/chunk/ChunkSection.patch

--- a/net/minecraft/world/level/chunk/ChunkSection.java
+++ b/net/minecraft/world/level/chunk/ChunkSection.java
@@ -190,6 +190,12 @@
         return (Holder) this.biomes.get(i, j, k);
     }
 
+    // CraftBukkit start
+    public void setBiome(int i, int j, int k, Holder<BiomeBase> biome) {
+        this.biomes.set(i, j, k, biome);
+    }
+    // CraftBukkit end
+
     public void fillBiomesFromNoise(BiomeResolver biomeresolver, Climate.Sampler climate_sampler, int i, int j) {
         DataPaletteBlock<Holder<BiomeBase>> datapaletteblock = this.getBiomes();