algoliasearch/src/main/java/com/algolia/search/saas/Client.java
public Request listIndexesAsync(@Nullable final RequestOptions requestOptions, @NonNull CompletionHandler completionHandler) {
        return new AsyncTaskRequest(completionHandler) {
            @NonNull
            @Override
            protected JSONObject run() throws AlgoliaException {
                return listIndexes(requestOptions);
            }
        }.start();
    }
public Request listIndexesAsync(@Nullable final RequestOptions requestOptions, @NonNull CompletionHandler completionHandler) {
        return new AsyncTaskRequest(completionHandler) {
            @NonNull
            @Override
            protected JSONObject run() throws AlgoliaException {
                return listIndexes(requestOptions);
            }
        }.start();
    }
List existing indexes.

@param requestOptions    Request-specific options.
@param completionHandler The listener that will be notified of the request's outcome.
@return A cancellable request.