SendInviteResult — недопустимое использование неполного типа ‘класс firebase :: Future & lt; firebase :: invites :: InvitesSender :: SendInviteResult & gt;’

На C ++, как отправить приглашение?

firebase::invites::InvitesSender *sender = new firebase::invites::InvitesSender(*_app);
sender->SetTitleText("Invite Friends");
sender->SetMessageText("Try my app today, and get 200 free coins!");
sender->SetCallToActionText("Download now!");
sender->SendInvite();

компилятор выдает ошибку:

error: invalid use of incomplete type 'class firebase::Future<firebase::invites::InvitesSender::SendInviteResult>'
sender->SendInvite();
firebase_cpp_sdk\include/firebase/invites/sender.h:12:7: error: declaration of 'class firebase::Future<firebase::invites::InvitesSender::SendInviteResult>'
class Future;