Angular 角度工作空间偏移

我正试着从角度8到角度9

因此，我命令如下

$ git diff src/tsconfig.app.json
diff --git a/src/tsconfig.app.json b/src/tsconfig.app.json
--- a/src/tsconfig.app.json
+++ b/src/tsconfig.app.json
@@ -5,8 +5,11 @@
     "baseUrl": "./",
     "types": []
   },
-  "exclude": [
-    "test.ts",
-    "**/*.spec.ts"
+  "files": [
+    "main.ts",
+    "polyfills.ts"
+  ],
+  "include": [
+    "src/**/*.d.ts"
   ]
 }

ng更新@angular/core@9@棱角/cli@9

在此日志中，将发生角度工作空间迁移

> Angular Workspace migration.
  Update an Angular CLI workspace to version 9.
  UPDATE angular.json (7164 bytes)
  UPDATE src/tsconfig.app.json (225 bytes)
  UPDATE package.json (2312 bytes)
√ Packages installed successfully.
  Migration completed.

tsconfig.app.json

更改如下

$ git diff src/tsconfig.app.json
diff --git a/src/tsconfig.app.json b/src/tsconfig.app.json
--- a/src/tsconfig.app.json
+++ b/src/tsconfig.app.json
@@ -5,8 +5,11 @@
     "baseUrl": "./",
     "types": []
   },
-  "exclude": [
-    "test.ts",
-    "**/*.spec.ts"
+  "files": [
+    "main.ts",
+    "polyfills.ts"
+  ],
+  "include": [
+    "src/**/*.d.ts"
   ]
 }

所以。。。问题:

为什么删除排除属性并添加包含属性？？