private static boolean canHandleRouting(FileSystemProvider provider) {
    if (provider instanceof RoutingAwareFileSystemProvider) {
      // `instanceof` is still faster than a successful cache hit.
      // Even if `instanceof` misses, its negative impact is negligible. See a benchmark in the commit message.
      return ((RoutingAwareFileSystemProvider)provider).canHandleRouting();
    }
    return ourCanHandleRoutingCache.computeIfAbsent(provider, MultiRoutingFileSystemProvider::canHandleRoutingImpl);
  }
private static boolean canHandleRouting(FileSystemProvider provider)