结构大修改，改成朴实无华的结构，不过度架构。能跑就行

Assets/Scripts/NBC/Asset/Editor/Builder/Gathers/GatherSingle.cs

@@ -0,0 +1,19 @@
+using System.Collections.Generic;
+
+namespace NBC.Asset.Editor
+{
+    [Bind(BundleMode.Single)]
+    public class GatherSingle : GatherBase
+    {
+        protected override BuildAsset[] Execute()
+        {
+            List<BuildAsset> assets = GetAssets();
+            foreach (var asset in assets)
+            {
+                asset.Bundle = GetBundleName(asset, GroupConfig.Name);
+            }
+
+            return assets.ToArray();
+        }
+    }
+}