Changed generic signature of GameRegistry.register methods to work around the type inference bug; updated all example mods to the new block/item registration method.

src/main/java/net/minecraftforge/fml/common/registry/GameData.java

@@ -210,32 +210,38 @@ public class GameData
     {
         return (BiMap<Block,Item>)getMain().iItemRegistry.getSlaveMap(BLOCK_TO_ITEM, BiMap.class);
     }
-    static <K extends IForgeRegistryEntry<K>> K register(K object, ResourceLocation location)
+
+    @SuppressWarnings("unchecked")
+    static <K extends IForgeRegistryEntry<K>> K register_impl(Object object, ResourceLocation location)
     {
         if (object == null)
         {
             FMLLog.getLogger().log(Level.ERROR, "Attempt to register a null object");
             throw new NullPointerException("Attempt to register a null object");
         }
-        object.setRegistryName(location);
-        return register(object);
+        ((K)object).setRegistryName(location);
+        // explicit type is needed for some reason
+        return GameData.<K>register_impl(object);
     }
 
-    static <K extends IForgeRegistryEntry<K>> K register(K object)
+    // argument is Object due to incorrect inferrence of the type if source level = 6, probably related to https://bugs.openjdk.java.net/browse/JDK-8026527
+    @SuppressWarnings("unchecked")
+    static <K extends IForgeRegistryEntry<K>> K register_impl(Object object)
     {
+        K castedObj = (K)object;
         if (object == null)
         {
             FMLLog.getLogger().log(Level.ERROR, "Attempt to register a null object");
             throw new NullPointerException("Attempt to register a null object");
         }
-        if (object.getRegistryName() == null)
+        if (castedObj.getRegistryName() == null)
         {
             FMLLog.getLogger().log(Level.ERROR, "Attempt to register object without having set a registry name {} (type {})", object, object.getClass().getName());
             throw new IllegalArgumentException(String.format("No registry name set for object %s (%s)", object, object.getClass().getName()));
         }
-        final IForgeRegistry<K> registry = PersistentRegistryManager.findRegistry(object);
-        registry.register(object);
-        return object;
+        final IForgeRegistry<K> registry = PersistentRegistryManager.findRegistry(castedObj);
+        registry.register(castedObj);
+        return castedObj;
     }
 
     @SuppressWarnings("unchecked")

src/main/java/net/minecraftforge/fml/common/registry/GameRegistry.java

@@ -140,9 +140,10 @@ public class GameRegistry
      * @throws IllegalArgumentException if the object is not yet named (use {@link #register(IForgeRegistryEntry, ResourceLocation)} instead)
      * @return The object
      */
-    public static <K extends IForgeRegistryEntry<K>> K register(K object)
+    @SuppressWarnings("unchecked")
+    public static <K extends IForgeRegistryEntry<?>> K register(K object)
     {
-        return GameData.register(object);
+        return (K)GameData.register_impl(object);
     }
 
     /**
@@ -159,9 +160,10 @@ public class GameRegistry
      * @throws IllegalStateException if the object already has an existing name (use {@link #register(IForgeRegistryEntry)} instead)
      * @return The object
      */
-    public static <K extends IForgeRegistryEntry<K>> K register(K object, ResourceLocation name)
+    @SuppressWarnings("unchecked")
+    public static <K extends IForgeRegistryEntry<?>> K register(K object, ResourceLocation name)
     {
-        return GameData.register(object, name);
+        return (K)GameData.register_impl(object, name);
     }