code: @Beta
    @Deprecated
    @GwtIncompatible // TODO
    public static <V, X extends Exception> CheckedFuture<V, X> immediateCheckedFuture(
        @Nullable V value) {
      return new ImmediateSuccessfulCheckedFuture<>(value);
    }
docs: TODO(b/72241893): Remove by 2019-01