PaperMC/paper-server/nms-patches/net/minecraft/world/item/ItemHanging.patch

--- a/net/minecraft/world/item/ItemHanging.java
+++ b/net/minecraft/world/item/ItemHanging.java
@@ -15,6 +15,11 @@
 import net.minecraft.world.level.World;
 import net.minecraft.world.level.gameevent.GameEvent;
 
+// CraftBukkit start
+import org.bukkit.entity.Player;
+import org.bukkit.event.hanging.HangingPlaceEvent;
+// CraftBukkit end
+
 public class ItemHanging extends Item {
 
     private final EntityTypes<? extends EntityHanging> type;
@@ -58,6 +63,18 @@
 
             if (((EntityHanging) object).survives()) {
                 if (!world.isClientSide) {
+                    // CraftBukkit start - fire HangingPlaceEvent
+                    Player who = (itemactioncontext.getPlayer() == null) ? null : (Player) itemactioncontext.getPlayer().getBukkitEntity();
+                    org.bukkit.block.Block blockClicked = world.getWorld().getBlockAt(blockposition.getX(), blockposition.getY(), blockposition.getZ());
+                    org.bukkit.block.BlockFace blockFace = org.bukkit.craftbukkit.block.CraftBlock.notchToBlockFace(enumdirection);
+
+                    HangingPlaceEvent event = new HangingPlaceEvent((org.bukkit.entity.Hanging) ((EntityHanging) object).getBukkitEntity(), who, blockClicked, blockFace, org.bukkit.craftbukkit.inventory.CraftItemStack.asBukkitCopy(itemstack));
+                    world.getCraftServer().getPluginManager().callEvent(event);
+
+                    if (event.isCancelled()) {
+                        return EnumInteractionResult.FAIL;
+                    }
+                    // CraftBukkit end
                     ((EntityHanging) object).playPlacementSound();
                     world.gameEvent(entityhuman, GameEvent.ENTITY_PLACE, blockposition);
                     world.addFreshEntity((Entity) object);