Start firing AttachCapabilitiesEvent<ItemStack> (#3645)

src/main/java/net/minecraftforge/event/AttachCapabilitiesEvent.java

@@ -40,8 +40,8 @@ import javax.annotation.Nonnull;
 public class AttachCapabilitiesEvent<T> extends GenericEvent<T>
 {
     private final T obj;
-    private final Map<ResourceLocation, ICapabilityProvider> caps = Maps.newLinkedHashMap();
-    private final Map<ResourceLocation, ICapabilityProvider> view = Collections.unmodifiableMap(caps);
+    final Map<ResourceLocation, ICapabilityProvider> caps;// package-private for ForgeEventFactory
+    private final Map<ResourceLocation, ICapabilityProvider> view;
 
     @SuppressWarnings("unchecked")
     @Deprecated
@@ -50,9 +50,16 @@ public class AttachCapabilitiesEvent<T> extends GenericEvent<T>
         this((Class<T>)Object.class, obj);
     }
     public AttachCapabilitiesEvent(Class<T> type, T obj)
+    {
+        this(type, obj, Maps.<ResourceLocation, ICapabilityProvider>newLinkedHashMap());
+    }
+    // package-private for ForgeEventFactory
+    AttachCapabilitiesEvent(Class<T> type, T obj, Map<ResourceLocation, ICapabilityProvider> caps)
     {
         super(type);
         this.obj = obj;
+        this.caps = caps;
+        this.view = Collections.unmodifiableMap(caps);
     }
 
     /**
@@ -126,10 +133,10 @@ public class AttachCapabilitiesEvent<T> extends GenericEvent<T>
     /**
      * A version of the parent event which is only fired for ItemStacks.
      */
+    @Deprecated
     public static class Item extends AttachCapabilitiesEvent<net.minecraft.item.Item>
     {
         private final net.minecraft.item.ItemStack stack;
-        @Deprecated
         private final net.minecraft.item.Item item;
         public Item(net.minecraft.item.Item item, @Nonnull  net.minecraft.item.ItemStack stack)
         {
@@ -137,7 +144,6 @@ public class AttachCapabilitiesEvent<T> extends GenericEvent<T>
             this.item = item;
             this.stack = stack;
         }
-        @Deprecated
         public net.minecraft.item.Item getItem()
         {
             return this.item;

src/main/java/net/minecraftforge/event/ForgeEventFactory.java

@@ -561,7 +561,13 @@ public class ForgeEventFactory
     @Nullable
     public static CapabilityDispatcher gatherCapabilities(Item item, ItemStack stack, ICapabilityProvider parent)
     {
-        return gatherCapabilities(new AttachCapabilitiesEvent.Item(item, stack), parent);
+        // first fire the legacy event
+        AttachCapabilitiesEvent.Item legacyEvent = new AttachCapabilitiesEvent.Item(item, stack);
+        MinecraftForge.EVENT_BUS.post(legacyEvent);
+
+        // fire new event with the caps that were already registered on the legacy event
+        AttachCapabilitiesEvent<ItemStack> event = new AttachCapabilitiesEvent<ItemStack>(ItemStack.class, stack, legacyEvent.caps);
+        return gatherCapabilities(event, parent);
     }
 
     @Nullable