Fix CreativeTab ordering and erronous adding to all item groups for some items.

src/main/java/appeng/block/networking/BlockEnergyCell.java

@@ -50,12 +50,12 @@ public class BlockEnergyCell extends AEBaseTileBlock<TileEnergyCell>
 	{
 		super.fillItemGroup( group, itemStacks );
 
-		final ItemStack charged = new ItemStack( this, 1 );
-        final CompoundNBT tag = charged.getOrCreateTag();
+		final ItemStack charged = new ItemStack(this, 1);
+		final CompoundNBT tag = charged.getOrCreateTag();
 		tag.putDouble("internalCurrentPower", this.getMaxPower());
 		tag.putDouble("internalMaxPower", this.getMaxPower());
 
-		itemStacks.add( charged );
+		itemStacks.add(charged);
 	}
 
 	public double getMaxPower()

src/main/java/appeng/bootstrap/BlockDefinitionBuilder.java

@@ -28,6 +28,7 @@ import java.util.function.Supplier;
 
 import javax.annotation.Nullable;
 
+import appeng.core.AEItemGroup;
 import net.minecraft.block.Block;
 import net.minecraft.item.BlockItem;
 import net.minecraft.item.Item;
@@ -63,7 +64,7 @@ class BlockDefinitionBuilder implements IBlockBuilder
 
 	private final EnumSet<AEFeature> features = EnumSet.noneOf( AEFeature.class );
 
-	private ItemGroup itemGroup = CreativeTab.instance;
+	private ItemGroup itemGroup = CreativeTab.INSTANCE;
 
 	private TileEntityDefinition tileEntityDefinition;
 
@@ -190,14 +191,21 @@ class BlockDefinitionBuilder implements IBlockBuilder
 			}
 		}
 
+		T definition;
 		if( block instanceof AEBaseTileBlock )
 		{
-			return (T) new TileDefinition( this.registryName, (AEBaseTileBlock) block, item, features );
+			definition = (T) new TileDefinition( this.registryName, (AEBaseTileBlock<?>) block, item, features );
 		}
 		else
 		{
-			return (T) new BlockDefinition( this.registryName, block, item, features );
+			definition = (T) new BlockDefinition( this.registryName, block, item, features );
 		}
+
+		if (itemGroup instanceof AEItemGroup) {
+			((AEItemGroup) itemGroup).add(definition);
+		}
+
+		return definition;
 	}
 
 	@Nullable

src/main/java/appeng/bootstrap/ItemDefinitionBuilder.java

@@ -28,13 +28,13 @@ import java.util.function.Function;
 import java.util.function.Supplier;
 
 import appeng.bootstrap.components.IInitComponent;
+import appeng.core.AEItemGroup;
 import net.minecraft.block.DispenserBlock;
 import net.minecraft.dispenser.IDispenseItemBehavior;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemGroup;
 
 import appeng.bootstrap.components.IItemRegistrationComponent;
-import appeng.bootstrap.components.IPostInitComponent;
 import appeng.core.AppEng;
 import appeng.core.CreativeTab;
 import appeng.api.features.AEFeature;
@@ -64,7 +64,7 @@ class ItemDefinitionBuilder implements IItemBuilder
 	@OnlyIn( Dist.CLIENT )
 	private ItemRendering itemRendering;
 
-	private ItemGroup itemGroup = CreativeTab.instance;
+	private ItemGroup itemGroup = CreativeTab.INSTANCE;
 
 	ItemDefinitionBuilder( FeatureFactory factory, String registryName, Function<Item.Properties, Item> itemFactory )
 	{
@@ -167,6 +167,10 @@ class ItemDefinitionBuilder implements IItemBuilder
 			this.itemRendering.apply( this.factory, item );
 		}
 
+		if (itemGroup instanceof AEItemGroup) {
+			((AEItemGroup) itemGroup).add(definition);
+		}
+
 		return definition;
 	}
 

src/main/java/appeng/core/AEItemGroup.java

@@ -0,0 +1,40 @@
+package appeng.core;
+
+import appeng.api.AEApi;
+import appeng.api.definitions.IBlocks;
+import appeng.api.definitions.IDefinitions;
+import appeng.api.definitions.IItemDefinition;
+import net.minecraft.item.ItemGroup;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.NonNullList;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class AEItemGroup extends ItemGroup {
+
+    private final List<IItemDefinition> itemDefs = new ArrayList<>();
+
+    public AEItemGroup(String label) {
+        super(label);
+    }
+
+    @Override
+    public ItemStack createIcon() {
+        final IDefinitions definitions = AEApi.instance().definitions();
+        final IBlocks blocks = definitions.blocks();
+        return blocks.controller().stack(1);
+    }
+
+    public void add(IItemDefinition itemDef) {
+        this.itemDefs.add(itemDef);
+    }
+
+    @Override
+    public void fill(NonNullList<ItemStack> items) {
+        for (IItemDefinition itemDef : this.itemDefs) {
+            itemDef.item().fillItemGroup(this, items);
+        }
+    }
+
+}

src/main/java/appeng/core/CreativeTab.java

@@ -19,31 +19,13 @@
 package appeng.core;
 
 
-import net.minecraft.item.ItemGroup;
-import net.minecraft.item.ItemStack;
-
-import appeng.api.AEApi;
-import appeng.api.definitions.IBlocks;
-import appeng.api.definitions.IDefinitions;
-
-
 public final class CreativeTab
 {
-	public static ItemGroup instance = null;
 
-	static void init()
-	{
-		instance = new ItemGroup( "appliedenergistics2" )
-		{
+	public static AEItemGroup INSTANCE;
 
-			@Override
-			public ItemStack createIcon()
-			{
-				final IDefinitions definitions = AEApi.instance().definitions();
-				final IBlocks blocks = definitions.blocks();
-				return blocks.controller().stack(1);
-			}
-
-		};
+	public static void init() {
+		INSTANCE = new AEItemGroup( "appliedenergistics2" );
 	}
+
 }

src/main/java/appeng/core/api/definitions/ApiParts.java

@@ -220,7 +220,7 @@ public final class ApiParts implements IParts
 
 	private <T extends IPart> IItemDefinition createPart(FeatureFactory registry, String id, PartType type, Function<ItemStack, T> factory) {
 		return registry.item(id, props -> new ItemPart<>(props, type, factory))
-				.itemGroup(CreativeTab.instance)
+				.itemGroup(CreativeTab.INSTANCE)
 				.rendering(new ItemPartRendering())
 				.build();
 	}
@@ -234,7 +234,7 @@ public final class ApiParts implements IParts
 			String id = color.registryPrefix + '_' + idSuffix;
 
 			IItemDefinition itemDef = registry.item(id, props -> new ColoredPartItem<>(props, type, factory, color))
-					.itemGroup(CreativeTab.instance)
+					.itemGroup(CreativeTab.INSTANCE)
 					.rendering(new ItemPartRendering(color))
 					.build();
 

src/main/java/appeng/items/misc/ItemPaintBall.java

@@ -81,6 +81,10 @@ public class ItemPaintBall extends AEBaseItem
 	@Override
 	public void fillItemGroup(ItemGroup group, NonNullList<ItemStack> itemStacks) {
 
+		if (!isInGroup(group)) {
+			return;
+		}
+
 		for( final AEColor c : AEColor.values() )
 		{
 			if( c != AEColor.TRANSPARENT )

src/main/java/appeng/items/tools/powered/powersink/AEBasePoweredItem.java

@@ -88,12 +88,14 @@ public abstract class AEBasePoweredItem extends AEBaseItem implements IAEItemPow
 	public void fillItemGroup(ItemGroup group, NonNullList<ItemStack> items) {
 		super.fillItemGroup(group, items);
 
-		final ItemStack charged = new ItemStack( this, 1 );
-        final CompoundNBT tag = charged.getOrCreateTag();
-		tag.putDouble(CURRENT_POWER_NBT_KEY, this.getAEMaxPower( charged ));
-		tag.putDouble(MAX_POWER_NBT_KEY, this.getAEMaxPower( charged ));
+		if (this.isInGroup(group)) {
+			final ItemStack charged = new ItemStack(this, 1);
+			final CompoundNBT tag = charged.getOrCreateTag();
+			tag.putDouble(CURRENT_POWER_NBT_KEY, this.getAEMaxPower(charged));
+			tag.putDouble(MAX_POWER_NBT_KEY, this.getAEMaxPower(charged));
 
-		items.add( charged );
+			items.add(charged);
+		}
 	}
 
 	@Override