Add InventoryPickupItemEvent. Adds BUKKIT-3798

By: Michael Limiero <mike5713@gmail.com>

paper-api/src/main/java/org/bukkit/event/inventory/InventoryPickupItemEvent.java

@@ -0,0 +1,58 @@
+package org.bukkit.event.inventory;
+
+import org.bukkit.entity.Item;
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.Event;
+import org.bukkit.event.HandlerList;
+import org.bukkit.inventory.Inventory;
+
+/**
+ * Called when a hopper or hopper minecart picks up a dropped item.
+ */
+public class InventoryPickupItemEvent extends Event implements Cancellable {
+    private static final HandlerList handlers = new HandlerList();
+    private boolean cancelled;
+    private final Inventory inventory;
+    private final Item item;
+
+    public InventoryPickupItemEvent(final Inventory inventory, final Item item) {
+        super();
+        this.inventory = inventory;
+        this.item = item;
+    }
+
+    /**
+     * Gets the Inventory that picked up the item
+     *
+     * @return Inventory
+     */
+    public Inventory getInventory() {
+        return inventory;
+    }
+
+    /**
+     * Gets the Item entity that was picked up
+     *
+     * @return Item
+     */
+    public Item getItem() {
+        return item;
+    }
+
+    public boolean isCancelled() {
+        return cancelled;
+    }
+
+    public void setCancelled(boolean cancel) {
+        this.cancelled = cancel;
+    }
+
+    @Override
+    public HandlerList getHandlers() {
+        return handlers;
+    }
+
+    public static HandlerList getHandlerList() {
+        return handlers;
+    }
+}