code: protected void checkPath(Path path) {
      URI thisUri = this.getUri();
      URI thatUri = path.toUri();
      String thatAuthority = thatUri.getAuthority();
      if (thatUri.getScheme() != null
          && thatUri.getScheme().equalsIgnoreCase(thisUri.getScheme())
          && thatUri.getPort() == NameNode.DEFAULT_PORT
          && thisUri.getPort() == -1
          && thatAuthority.substring(0,thatAuthority.indexOf(":"))
          .equalsIgnoreCase(thisUri.getAuthority()))
        return;
      super.checkPath(path);
    }
docs: Permit paths which explicitly specify the default port.