algoliasearch/src/offline/java/com/algolia/search/saas/OfflineClient.java
public Request listIndexesOfflineAsync(@NonNull CompletionHandler completionHandler) {
        return new AsyncTaskRequest(completionHandler) {
            @NonNull
            @Override
            protected JSONObject run() throws AlgoliaException {
                return listIndexesOfflineSync();
            }
        }.start();
    }
public Request listIndexesOfflineAsync(@NonNull CompletionHandler completionHandler) {
        return new AsyncTaskRequest(completionHandler) {
            @NonNull
            @Override
            protected JSONObject run() throws AlgoliaException {
                return listIndexesOfflineSync();
            }
        }.start();
    }
List existing offline indices.
Only indices that *actually exist* on disk are listed. If an instance was created but never synced or written
to, it will not appear in the list.

**Note:** This applies both to {@link MirroredIndex} and {@link OfflineIndex} instances.

@param completionHandler The listener that will be notified of the request's outcome.
@return A cancellable request.