PaperMC/nms-patches/BlockCoralFanWall.patch

--- a/net/minecraft/server/BlockCoralFanWall.java
+++ b/net/minecraft/server/BlockCoralFanWall.java
@@ -17,6 +17,11 @@
 
     public void a(IBlockData iblockdata, World world, BlockPosition blockposition, Random random) {
         if (!b_(iblockdata, world, blockposition)) {
+            // CraftBukkit start
+            if (org.bukkit.craftbukkit.event.CraftEventFactory.callBlockFadeEvent(world, blockposition, this.c.getBlockData().set(BlockCoralFanWall.b, Boolean.valueOf(false)).set(BlockCoralFanWall.a, iblockdata.get(BlockCoralFanWall.a))).isCancelled()) {
+                return;
+            }
+            // CraftBukkit end
             world.setTypeAndData(blockposition, (IBlockData) ((IBlockData) this.c.getBlockData().set(BlockCoralFanWall.b, Boolean.valueOf(false))).set(BlockCoralFanWall.a, iblockdata.get(BlockCoralFanWall.a)), 2);
         }