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

--- a/net/minecraft/world/item/ItemSnowball.java
+++ b/net/minecraft/world/item/ItemSnowball.java
@@ -19,19 +19,32 @@
     public InteractionResultWrapper<ItemStack> use(World world, EntityHuman entityhuman, EnumHand enumhand) {
         ItemStack itemstack = entityhuman.getItemInHand(enumhand);
 
-        world.playSound((EntityHuman) null, entityhuman.getX(), entityhuman.getY(), entityhuman.getZ(), SoundEffects.SNOWBALL_THROW, SoundCategory.NEUTRAL, 0.5F, 0.4F / (world.getRandom().nextFloat() * 0.4F + 0.8F));
+        // CraftBukkit - moved down
+        // world.playSound((EntityHuman) null, entityhuman.getX(), entityhuman.getY(), entityhuman.getZ(), SoundEffects.SNOWBALL_THROW, SoundCategory.NEUTRAL, 0.5F, 0.4F / (world.getRandom().nextFloat() * 0.4F + 0.8F));
         if (!world.isClientSide) {
             EntitySnowball entitysnowball = new EntitySnowball(world, entityhuman);
 
             entitysnowball.setItem(itemstack);
             entitysnowball.shootFromRotation(entityhuman, entityhuman.getXRot(), entityhuman.getYRot(), 0.0F, 1.5F, 1.0F);
-            world.addFreshEntity(entitysnowball);
+            if (world.addFreshEntity(entitysnowball)) {
+                if (!entityhuman.getAbilities().instabuild) {
+                    itemstack.shrink(1);
+                }
+
+                world.playSound((EntityHuman) null, entityhuman.getX(), entityhuman.getY(), entityhuman.getZ(), SoundEffects.SNOWBALL_THROW, SoundCategory.NEUTRAL, 0.5F, 0.4F / (world.getRandom().nextFloat() * 0.4F + 0.8F));
+            } else if (entityhuman instanceof net.minecraft.server.level.EntityPlayer) {
+                ((net.minecraft.server.level.EntityPlayer) entityhuman).getBukkitEntity().updateInventory();
+            }
         }
+        // CraftBukkit end
 
         entityhuman.awardStat(StatisticList.ITEM_USED.get(this));
+        // CraftBukkit start - moved up
+        /*
         if (!entityhuman.getAbilities().instabuild) {
             itemstack.shrink(1);
         }
+        */
 
         return InteractionResultWrapper.sidedSuccess(itemstack, world.isClientSide());
     }