Migrate EMPTY methods to factories.

Signed-off-by: Chris Sanders <[email protected]>

Author: Zidane

src/main/java/org/spongepowered/api/block/BlockSnapshot.java

@@ -40,22 +40,15 @@
 
 import java.util.Optional;
 import java.util.UUID;
-import java.util.function.Supplier;
 
 /**
  * An immutable representation of a {@link BlockState} and any extra data that
  * may be associated with it, including {@link BlockEntity} related data.
  */
 public interface BlockSnapshot extends LocatableSnapshot<BlockSnapshot> {
 
-    /**
-     * Represents a {@link BlockSnapshot} with the default state of
-     * {@link BlockTypes#AIR} and a {@link ServerLocation} that cannot be determined.
-     */
-    Supplier<BlockSnapshot> NONE = BlockSnapshot::empty;
-
     static BlockSnapshot empty() {
-        return Sponge.game().builderProvider().provide(Builder.class).empty();
+        return Sponge.game().factoryProvider().provide(Factory.class).empty();
     }
 
     /**
@@ -205,6 +198,9 @@ interface Builder extends SerializableDataHolderBuilder.Immutable<BlockSnapshot,
          * @return This builder, for chaining
          */
         Builder notifier(UUID uuid);
+    }
+
+    interface Factory {
 
         BlockSnapshot empty();
     }

src/main/java/org/spongepowered/api/item/inventory/ItemStack.java

@@ -37,7 +37,6 @@
 import org.spongepowered.api.entity.attribute.AttributeModifier;
 import org.spongepowered.api.entity.attribute.type.AttributeType;
 import org.spongepowered.api.item.ItemType;
-import org.spongepowered.api.item.ItemTypes;
 import org.spongepowered.api.item.inventory.equipment.EquipmentType;
 import org.spongepowered.api.registry.DefaultedRegistryReference;
 
@@ -59,6 +58,15 @@
  */
 public interface ItemStack extends SerializableDataHolder.Mutable {
 
+    /**
+     * Returns an empty {@link ItemStack}.
+     *
+     * @return The empty ItemStack
+     */
+    static ItemStack empty() {
+        return Sponge.game().factoryProvider().provide(Factory.class).empty();
+    }
+
     /**
      * Creates a new {@link Builder} to build an {@link ItemStack}.
      *
@@ -112,15 +120,6 @@ static ItemStack of(ItemType itemType) {
         return ItemStack.of(itemType, 1);
     }
 
-    /**
-     * Returns an empty {@link ItemStack}.
-     *
-     * @return The empty ItemStack
-     */
-    static ItemStack empty() {
-        return ItemStack.builder().itemType(ItemTypes.AIR).build();
-    }
-
     /**
      * Gets the {@link ItemType} of this {@link ItemStack}.
      *
@@ -413,4 +412,9 @@ default Builder apply(Predicate<Builder> predicate, Consumer<Builder> consumer)
         @Override
         ItemStack build() throws IllegalStateException;
     }
+
+    interface Factory {
+
+        ItemStack empty();
+    }
 }