--- a/net/minecraft/world/biome/Biome.java
+++ b/net/minecraft/world/biome/Biome.java
@@ -68,7 +68,7 @@
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 
-public class Biome {
+public class Biome extends net.minecraftforge.registries.ForgeRegistryEntry<Biome> {
    public static final Logger field_150586_aC = LogManager.getLogger();
    public static final Codec<Biome> field_235051_b_ = RecordCodecBuilder.create((p_235064_0_) -> {
       return p_235064_0_.group(Biome.RainType.field_235121_d_.fieldOf("precipitation").forGetter((p_235088_0_) -> {
@@ -221,7 +221,7 @@
    }
 
    protected void func_201866_a(EntityClassification p_201866_1_, Biome.SpawnListEntry p_201866_2_) {
-      this.field_201880_ax.get(p_201866_1_).add(p_201866_2_);
+      this.field_201880_ax.computeIfAbsent(p_201866_1_, k -> Lists.newArrayList()).add(p_201866_2_);
    }
 
    protected void func_235059_a_(EntityType<?> p_235059_1_, double p_235059_2_, double p_235059_4_) {
@@ -229,7 +229,7 @@
    }
 
    public List<Biome.SpawnListEntry> func_76747_a(EntityClassification p_76747_1_) {
-      return this.field_201880_ax.get(p_76747_1_);
+      return this.field_201880_ax.computeIfAbsent(p_76747_1_, k -> Lists.newArrayList());
    }
 
    @Nullable
@@ -308,7 +308,7 @@
       } else {
          if (p_201850_2_.func_177956_o() >= 0 && p_201850_2_.func_177956_o() < 256 && p_201850_1_.func_226658_a_(LightType.BLOCK, p_201850_2_) < 10) {
             BlockState blockstate = p_201850_1_.func_180495_p(p_201850_2_);
-            if (blockstate.func_196958_f() && Blocks.field_150433_aE.func_176223_P().func_196955_c(p_201850_1_, p_201850_2_)) {
+            if (blockstate.isAir(p_201850_1_, p_201850_2_) && Blocks.field_150433_aE.func_176223_P().func_196955_c(p_201850_1_, p_201850_2_)) {
                return true;
             }
          }
@@ -589,6 +589,17 @@
       }
    }
 
+   public Biome getRiver() {
+      if (this == Biomes.field_76774_n) return Biomes.field_76777_m;
+      if (this == Biomes.field_76789_p || this == Biomes.field_76788_q) return Biomes.field_76788_q;
+      return Biomes.field_76781_i;
+   }
+
+   @Nullable
+   public Biome getHill(net.minecraft.world.gen.INoiseRandom rand) {
+      return null;
+   }
+
    public static class Builder {
       @Nullable
       private ConfiguredSurfaceBuilder<?> field_205422_a;
