frontend-plugin-api: add explicit ApiRef plugin ownership

Add the new frontend ApiRef builder form while preserving compatibility with existing refs, and let frontend apps resolve API ownership through an explicit pluginId when provided.

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

packages/frontend-internal/src/apis/OpaqueApiRef.ts

@@ -1,28 +0,0 @@
-/*
- * Copyright 2025 The Backstage Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import { ApiRef } from '@backstage/frontend-plugin-api';
-import { OpaqueType } from '@internal/opaque';
-
-export const OpaqueApiRef = OpaqueType.create<{
-  public: ApiRef<unknown>;
-  versions: {
-    readonly version: 'v1';
-  };
-}>({
-  type: '@backstage/ApiRef',
-  versions: ['v1'],
-});

packages/frontend-internal/src/apis/index.ts

@@ -1,17 +0,0 @@
-/*
- * Copyright 2025 The Backstage Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-export { OpaqueApiRef } from './OpaqueApiRef';

packages/frontend-internal/src/index.ts

@@ -14,6 +14,5 @@
  * limitations under the License.
  */
 
-export * from './apis';
 export * from './routing';
 export * from './wiring';