Add Beacon block state for hopper events. Fixes BUKKIT-3932

src/main/java/net/minecraft/server/TileEntityBeacon.java

@@ -22,7 +22,7 @@ public class TileEntityBeacon extends TileEntity implements IInventory {
     private int maxStack = MAX_STACK;
 
     public ItemStack[] getContents() {
-        return null;
+        return new ItemStack[] { this.h }; // Should be inventorySlot
     }
 
     public void onOpen(CraftHumanEntity who) {

src/main/java/org/bukkit/craftbukkit/block/CraftBeacon.java

@@ -0,0 +1,37 @@
+package org.bukkit.craftbukkit.block;
+
+import net.minecraft.server.TileEntityBeacon;
+
+import org.bukkit.block.Block;
+import org.bukkit.block.Beacon;
+import org.bukkit.craftbukkit.CraftWorld;
+import org.bukkit.craftbukkit.inventory.CraftInventory;
+import org.bukkit.inventory.Inventory;
+
+public class CraftBeacon extends CraftBlockState implements Beacon {
+    private final CraftWorld world;
+    private final TileEntityBeacon beacon;
+
+    public CraftBeacon(final Block block) {
+        super(block);
+
+        world = (CraftWorld) block.getWorld();
+        beacon = (TileEntityBeacon) world.getTileEntityAt(getX(), getY(), getZ());
+    }
+
+    public Inventory getInventory() {
+        return new CraftInventory(beacon);
+    }
+
+    @Override
+    public boolean update(boolean force) {
+        boolean result = super.update(force);
+
+        if (result) {
+            beacon.update();
+        }
+
+        return result;
+    }
+}
+

src/main/java/org/bukkit/craftbukkit/block/CraftBlock.java

@@ -265,6 +265,8 @@ public class CraftBlock implements Block {
             return new CraftSkull(this);
         case COMMAND:
             return new CraftCommandBlock(this);
+        case BEACON:
+            return new CraftBeacon(this);
         default:
             return new CraftBlockState(this);
         }