Add an event for inspecting items too

We've had one for blocks for ever after all.

src/main/java/dan200/computercraft/api/turtle/event/TurtleInspectItemEvent.java

@@ -0,0 +1,74 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.api.turtle.event;
+
+import dan200.computercraft.api.lua.ILuaContext;
+import dan200.computercraft.api.peripheral.IComputerAccess;
+import dan200.computercraft.api.turtle.ITurtleAccess;
+import net.minecraft.item.ItemStack;
+
+import javax.annotation.Nonnull;
+import java.util.Map;
+import java.util.Objects;
+
+/**
+ * Fired when a turtle gathers data on an item in its inventory.
+ *
+ * You may prevent items being inspected, or add additional information to the result. Be aware that this is fired on
+ * the computer thread, and so any operations on it must be thread safe.
+ *
+ * @see TurtleAction#INSPECT_ITEM
+ */
+public class TurtleInspectItemEvent extends TurtleActionEvent
+{
+    private final ItemStack stack;
+    private final Map<String, Object> data;
+
+    public TurtleInspectItemEvent( @Nonnull ITurtleAccess turtle, @Nonnull ItemStack stack, @Nonnull Map<String, Object> data )
+    {
+        super( turtle, TurtleAction.INSPECT_ITEM );
+
+        Objects.requireNonNull( stack, "stack cannot be null" );
+        Objects.requireNonNull( data, "data cannot be null" );
+        this.stack = stack;
+        this.data = data;
+    }
+
+    /**
+     * The item which is currently being inspected.
+     *
+     * @return The item stack which is being inspected. This should <b>not</b> be modified.
+     */
+    @Nonnull
+    public ItemStack getStack()
+    {
+        return stack;
+    }
+
+    /**
+     * Get the "inspection data" from this item, which will be returned to the user.
+     *
+     * @return This items's inspection data.
+     */
+    @Nonnull
+    public Map<String, Object> getData()
+    {
+        return data;
+    }
+
+    /**
+     * Add new information to the inspection result. Note this will override fields with the same name.
+     *
+     * @param newData The data to add. Note all values should be convertible to Lua (see
+     *                {@link dan200.computercraft.api.peripheral.IPeripheral#callMethod(IComputerAccess, ILuaContext, int, Object[])}).
+     */
+    public void addData( @Nonnull Map<String, ?> newData )
+    {
+        Objects.requireNonNull( newData, "newData cannot be null" );
+        data.putAll( newData );
+    }
+}

src/main/java/dan200/computercraft/api/turtle/event/TurtleInventoryEvent.java

@@ -76,13 +76,12 @@ public abstract class TurtleInventoryEvent extends TurtleBlockEvent
         /**
          * The item which will be inserted into the inventory/dropped on the ground.
          *
-         * Note that this is a copy of the original stack, and so should not be modified, as that will have no effect.
-         *
-         * @return The item stack which will be dropped.
+         * @return The item stack which will be dropped. This should <b>not</b> be modified.
          */
+        @Nonnull
         public ItemStack getStack()
         {
-            return stack.copy();
+            return stack;
         }
     }
 }