Beta API questions (adding an extension)

In Jigsaw Alpha5, I used to do something like the following to
programmatically add an extension resource:

    // Add extension resources
    ResourceIndexer indexer = server.getIndexer();
    // Add extension resource for .exe
    if (indexer.loadExtension("exe") == null) {
      addExtension ("exe",
                    new MimeType ("application",
                                  "x-msdownload"),
                    indexer);
    }

where addExtension is defined as:

  static void addExtension (String extString,
                            MimeType type,
                            ResourceIndexer indexer) {
    FileResource ext = new FileResource();
    ext.setValue ("identifier", extString);
    indexer.registerExtension(ext);
    ext.setValue ("content-type", type);
    indexer.save();
    System.out.println("Added " + extString +
                       " extension resource to Jigsaw");
  }

How would I do it now in the beta API?

Thanks in advance.

-Mark