plugins/*-backend: flip around alpha exports to stable

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

plugins/app-backend/report-alpha.api.md

@@ -5,9 +5,13 @@
 ```ts
 import { BackendFeature } from '@backstage/backend-plugin-api';
 
-// @alpha
-const appPlugin: BackendFeature;
-export default appPlugin;
+// @alpha (undocumented)
+const _appPlugin: BackendFeature;
+export default _appPlugin;
+
+// Warnings were encountered during analysis:
+//
+// src/alpha.d.ts:2:15 - (ae-undocumented) Missing documentation for "_appPlugin".
 
 // (No @packageDocumentation comment for this package)
 ```

plugins/app-backend/report.api.md

@@ -12,13 +12,13 @@ import { HttpAuthService } from '@backstage/backend-plugin-api';
 import { LoggerService } from '@backstage/backend-plugin-api';
 import { RootConfigService } from '@backstage/backend-plugin-api';
 
+// @public
+const appPlugin: BackendFeature;
+export default appPlugin;
+
 // @public @deprecated (undocumented)
 export function createRouter(options: RouterOptions): Promise<express.Router>;
 
-// @public (undocumented)
-const _feature: BackendFeature;
-export default _feature;
-
 // @public @deprecated (undocumented)
 export interface RouterOptions {
   appPackageName: string;
@@ -38,7 +38,6 @@ export interface RouterOptions {
 
 // Warnings were encountered during analysis:
 //
-// src/index.d.ts:8:15 - (ae-undocumented) Missing documentation for "_feature".
 // src/service/router.d.ts:9:1 - (ae-undocumented) Missing documentation for "RouterOptions".
 // src/service/router.d.ts:10:5 - (ae-undocumented) Missing documentation for "config".
 // src/service/router.d.ts:11:5 - (ae-undocumented) Missing documentation for "logger".

plugins/app-backend/src/alpha.ts

@@ -14,4 +14,8 @@
  * limitations under the License.
  */
 
-export { appPlugin as default } from './service/appPlugin';
+import { appPlugin } from './service/appPlugin';
+
+/** @alpha */
+const _appPlugin = appPlugin;
+export default _appPlugin;

plugins/app-backend/src/index.ts

@@ -14,16 +14,11 @@
  * limitations under the License.
  */
 
-import { appPlugin as feature } from './service/appPlugin';
-
 /**
  * A Backstage backend plugin that serves the Backstage frontend app
  *
  * @packageDocumentation
  */
 
+export { appPlugin as default } from './service/appPlugin';
 export * from './service/router';
-
-/** @public */
-const _feature = feature;
-export default _feature;

plugins/app-backend/src/service/appPlugin.ts

@@ -28,7 +28,7 @@ import { ConfigSchema } from '@backstage/config-loader';
 
 /**
  * The App plugin is responsible for serving the frontend app bundle and static assets.
- * @alpha
+ * @public
  */
 export const appPlugin = createBackendPlugin({
   pluginId: 'app',