public static CompletableFuture<List<InterfaceType>> superinterfaces(InterfaceType iface) {
    if (iface instanceof InterfaceTypeImpl && isAsyncEnabled()) {
      return ((InterfaceTypeImpl)iface).superinterfacesAsync();
    }
    return completedFuture(iface.superinterfaces());
  }
public static CompletableFuture<List<InterfaceType>> superinterfaces(InterfaceType iface)