craftbukkit/nms-patches/net/minecraft/world/level/block/BlockDirtSnowSpreadable.patch

--- a/net/minecraft/world/level/block/BlockDirtSnowSpreadable.java
+++ b/net/minecraft/world/level/block/BlockDirtSnowSpreadable.java
@@ -40,6 +40,11 @@
     @Override
     public void randomTick(IBlockData iblockdata, WorldServer worldserver, BlockPosition blockposition, RandomSource randomsource) {
         if (!canBeGrass(iblockdata, worldserver, blockposition)) {
+            // CraftBukkit start
+            if (org.bukkit.craftbukkit.event.CraftEventFactory.callBlockFadeEvent(worldserver, blockposition, Blocks.DIRT.defaultBlockState()).isCancelled()) {
+                return;
+            }
+            // CraftBukkit end
             worldserver.setBlockAndUpdate(blockposition, Blocks.DIRT.defaultBlockState());
         } else {
             if (worldserver.getMaxLocalRawBrightness(blockposition.above()) >= 9) {
@@ -49,7 +54,7 @@
                     BlockPosition blockposition1 = blockposition.offset(randomsource.nextInt(3) - 1, randomsource.nextInt(5) - 3, randomsource.nextInt(3) - 1);
 
                     if (worldserver.getBlockState(blockposition1).is(Blocks.DIRT) && canPropagate(iblockdata1, worldserver, blockposition1)) {
-                        worldserver.setBlockAndUpdate(blockposition1, (IBlockData) iblockdata1.setValue(BlockDirtSnowSpreadable.SNOWY, worldserver.getBlockState(blockposition1.above()).is(Blocks.SNOW)));
+                        org.bukkit.craftbukkit.event.CraftEventFactory.handleBlockSpreadEvent(worldserver, blockposition, blockposition1, (IBlockData) iblockdata1.setValue(BlockDirtSnowSpreadable.SNOWY, worldserver.getBlockState(blockposition1.above()).is(Blocks.SNOW))); // CraftBukkit
                     }
                 }
             }