Paper/paper-server/patches/sources/net/minecraft/world/item/SnowballItem.java.patch

--- a/net/minecraft/world/item/SnowballItem.java
+++ b/net/minecraft/world/item/SnowballItem.java
@@ -23,22 +_,38 @@
     @Override
     public InteractionResult use(Level level, Player player, InteractionHand hand) {
         ItemStack itemInHand = player.getItemInHand(hand);
-        level.playSound(
-            null,
-            player.getX(),
-            player.getY(),
-            player.getZ(),
-            SoundEvents.SNOWBALL_THROW,
-            SoundSource.NEUTRAL,
-            0.5F,
-            0.4F / (level.getRandom().nextFloat() * 0.4F + 0.8F)
-        );
+        // CraftBukkit start - moved down
         if (level instanceof ServerLevel serverLevel) {
-            Projectile.spawnProjectileFromRotation(Snowball::new, serverLevel, itemInHand, player, 0.0F, PROJECTILE_SHOOT_POWER, 1.0F);
+            // Paper start - PlayerLaunchProjectileEvent
+            final Projectile.Delayed<Snowball> snowball = Projectile.spawnProjectileFromRotationDelayed(Snowball::new, serverLevel, itemInHand, player, 0.0F, SnowballItem.PROJECTILE_SHOOT_POWER, 1.0F);
+            com.destroystokyo.paper.event.player.PlayerLaunchProjectileEvent event = new com.destroystokyo.paper.event.player.PlayerLaunchProjectileEvent((org.bukkit.entity.Player) player.getBukkitEntity(), org.bukkit.craftbukkit.inventory.CraftItemStack.asCraftMirror(itemInHand), (org.bukkit.entity.Projectile) snowball.projectile().getBukkitEntity());
+            if (event.callEvent() && snowball.attemptSpawn()) {
+                player.awardStat(Stats.ITEM_USED.get(this));
+                if (event.shouldConsume()) {
+                    itemInHand.consume(1, player);
+                } else if (player instanceof net.minecraft.server.level.ServerPlayer) {
+                    ((net.minecraft.server.level.ServerPlayer) player).getBukkitEntity().updateInventory();
+                }
+            // Paper end - PlayerLaunchProjectileEvent
+
+                level.playSound(
+                    null,
+                    player.getX(),
+                    player.getY(),
+                    player.getZ(),
+                    SoundEvents.SNOWBALL_THROW,
+                    SoundSource.NEUTRAL,
+                    0.5F,
+                    0.4F / (level.getRandom().nextFloat() * 0.4F + 0.8F)
+                );
+            } else { if (player instanceof net.minecraft.server.level.ServerPlayer) { // Paper - PlayerLaunchProjectileEvent - return fail
+                ((net.minecraft.server.level.ServerPlayer) player).getBukkitEntity().updateInventory();
+            } return InteractionResult.FAIL; } // Paper - PlayerLaunchProjectileEvent - return fail
+            // CraftBukkit end
         }
 
-        player.awardStat(Stats.ITEM_USED.get(this));
-        itemInHand.consume(1, player);
+        // Paper - PlayerLaunchProjectileEvent - moved up
+        // itemInHand.consume(1, player); // CraftBukkit - moved up
         return InteractionResult.SUCCESS;
     }