--- a/net/minecraft/world/inventory/ContainerGrindstone.java
+++ b/net/minecraft/world/inventory/ContainerGrindstone.java
@@ -19,8 +19,30 @@
 import net.minecraft.world.level.block.Blocks;
 import net.minecraft.world.phys.Vec3D;
 
+// CraftBukkit start
+import org.bukkit.Location;
+import org.bukkit.craftbukkit.inventory.CraftInventoryGrindstone;
+import org.bukkit.craftbukkit.inventory.CraftInventoryView;
+import org.bukkit.entity.Player;
+// CraftBukkit end
+
 public class ContainerGrindstone extends Container {
 
+    // CraftBukkit start
+    private CraftInventoryView bukkitEntity = null;
+    private Player player;
+
+    @Override
+    public CraftInventoryView getBukkitView() {
+        if (bukkitEntity != null) {
+            return bukkitEntity;
+        }
+
+        CraftInventoryGrindstone inventory = new CraftInventoryGrindstone(this.repairSlots, this.resultSlots);
+        bukkitEntity = new CraftInventoryView(this.player, inventory, this);
+        return bukkitEntity;
+    }
+    // CraftBukkit end
     public static final int MAX_NAME_LENGTH = 35;
     public static final int INPUT_SLOT = 0;
     public static final int ADDITIONAL_SLOT = 1;
@@ -46,6 +68,13 @@
                 super.setChanged();
                 ContainerGrindstone.this.slotsChanged(this);
             }
+
+            // CraftBukkit start
+            @Override
+            public Location getLocation() {
+                return containeraccess.getLocation();
+            }
+            // CraftBukkit end
         };
         this.access = containeraccess;
         this.addSlot(new Slot(this.repairSlots, 0, 49, 19) {
@@ -124,6 +153,7 @@
             this.addSlot(new Slot(playerinventory, j, 8 + j * 18, 142));
         }
 
+        player = (Player) playerinventory.player.getBukkitEntity(); // CraftBukkit
     }
 
     @Override
@@ -145,7 +175,7 @@
             boolean flag2 = !itemstack.isEmpty() && !itemstack.is(Items.ENCHANTED_BOOK) && !itemstack.isEnchanted() || !itemstack1.isEmpty() && !itemstack1.is(Items.ENCHANTED_BOOK) && !itemstack1.isEnchanted();
 
             if (itemstack.getCount() > 1 || itemstack1.getCount() > 1 || !flag1 && flag2) {
-                this.resultSlots.setItem(0, ItemStack.EMPTY);
+                org.bukkit.craftbukkit.event.CraftEventFactory.callPrepareGrindstoneEvent(getBukkitView(), ItemStack.EMPTY); // CraftBukkit
                 this.broadcastChanges();
                 return;
             }
@@ -156,7 +186,7 @@
 
             if (flag1) {
                 if (!itemstack.is(itemstack1.getItem())) {
-                    this.resultSlots.setItem(0, ItemStack.EMPTY);
+                    org.bukkit.craftbukkit.event.CraftEventFactory.callPrepareGrindstoneEvent(getBukkitView(), ItemStack.EMPTY); // CraftBukkit
                     this.broadcastChanges();
                     return;
                 }
@@ -170,7 +200,7 @@
                 itemstack2 = this.mergeEnchants(itemstack, itemstack1);
                 if (!itemstack2.isDamageableItem()) {
                     if (!ItemStack.matches(itemstack, itemstack1)) {
-                        this.resultSlots.setItem(0, ItemStack.EMPTY);
+                        org.bukkit.craftbukkit.event.CraftEventFactory.callPrepareGrindstoneEvent(getBukkitView(), ItemStack.EMPTY); // CraftBukkit
                         this.broadcastChanges();
                         return;
                     }
@@ -183,12 +213,12 @@
                 i = flag3 ? itemstack.getDamageValue() : itemstack1.getDamageValue();
                 itemstack2 = flag3 ? itemstack : itemstack1;
             }
-
-            this.resultSlots.setItem(0, this.removeNonCurses(itemstack2, i, b0));
+            org.bukkit.craftbukkit.event.CraftEventFactory.callPrepareGrindstoneEvent(getBukkitView(), this.removeNonCurses(itemstack2, i, b0)); // CraftBukkit
         } else {
-            this.resultSlots.setItem(0, ItemStack.EMPTY);
+            org.bukkit.craftbukkit.event.CraftEventFactory.callPrepareGrindstoneEvent(getBukkitView(), ItemStack.EMPTY); // CraftBukkit
         }
 
+        sendAllDataToRemote(); // CraftBukkit - SPIGOT-6686: Always send completed inventory to stay in sync with client
         this.broadcastChanges();
     }
 
@@ -250,6 +280,7 @@
 
     @Override
     public boolean stillValid(EntityHuman entityhuman) {
+        if (!this.checkReachable) return true; // CraftBukkit
         return stillValid(this.access, entityhuman, Blocks.GRINDSTONE);
     }