Fix #443

Temp as it's performance-degrading, but works well enough for now

worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_15/BukkitGetBlocks_1_15.java

@@ -75,6 +75,8 @@ public class BukkitGetBlocks_1_15 extends CharGetBlocks {
     public Chunk nmsChunk;
     public WorldServer world;
     public int X, Z;
+    //This is (hopefully) a temp fix for random blocks returning the wrong biome. Static because it was seemingly using the wrong chunk to return the biome value.
+    private static final Object biomeLock = new Object();
 
     public BukkitGetBlocks_1_15(World world, int X, int Z) {
         this(((CraftWorld) world).getHandle(), X, Z);
@@ -106,8 +108,10 @@ public class BukkitGetBlocks_1_15 extends CharGetBlocks {
         } else {
             base = index.getBiome(x >> 2, y >> 2, z >> 2);
         }
+        synchronized (biomeLock) {
             return base != null ? BukkitAdapter.adapt(CraftBlock.biomeBaseToBiome(base)) : null;
         }
+    }
 
     @Override
     public CompoundTag getTile(int x, int y, int z) {

worldedit-bukkit/src/main/java/com/boydti/fawe/bukkit/adapter/mc1_15_2/BukkitGetBlocks_1_15_2.java

@@ -80,6 +80,8 @@ public class BukkitGetBlocks_1_15_2 extends CharGetBlocks {
     public Chunk nmsChunk;
     public WorldServer world;
     public int X, Z;
+    //This is (hopefully) a temp fix for random blocks returning the wrong biome. Static because it was seemingly using the wrong chunk to return the biome value.
+    private static final Object biomeLock = new Object();
 
     public BukkitGetBlocks_1_15_2(World world, int X, int Z) {
         this(((CraftWorld) world).getHandle(), X, Z);
@@ -111,8 +113,10 @@ public class BukkitGetBlocks_1_15_2 extends CharGetBlocks {
         } else {
             base = index.getBiome(x >> 2, y >> 2, z >> 2);
         }
+        synchronized (biomeLock) {
             return base != null ? BukkitAdapter.adapt(CraftBlock.biomeBaseToBiome(base)) : null;
         }
+    }
 
     @Override
     public CompoundTag getTile(int x, int y, int z) {