code: @Override
    public ApiFuture<Void> deleteSnapshotAsync(DeleteSnapshotRequest request) {
      return ApiFutures.transform(baseAdminClient.deleteSnapshotCallable().futureCall(request),
          new ApiFunction<Empty, Void>() {
            @Override
            public Void apply(Empty input) {
              return null;
            }
          }, directExecutor());
    }
docs: {@inheritDoc}