code: public ApplicationPropertySet admin_getAppProperties(EnumSet<ApplicationProperty> properties)
      throws FacebookException, IOException {
      if (null == properties || properties.isEmpty()) {
        throw new IllegalArgumentException("expecting a non-empty set of application properties");
      }
  
      JSONArray propList = new JSONArray();
      for (ApplicationProperty prop : properties) {
        propList.add(prop.propertyName());
      }
  
      String propJson =
        extractString(this.callMethod(FacebookMethod.ADMIN_GET_APP_PROPERTIES, 
                      new Pair<String, CharSequence>("properties", propList.toString())));
      return new ApplicationPropertySet(propJson);
    }
docs: Gets property values previously set for an application on either the Facebook Developer application or
  the with the <code>admin.setAppProperties</code> call.
  A session is not required to use this method.
  @param properties an enumeration of the properties to get
  @return an ApplicationPropertySet
  @see ApplicationProperty
  @see <a href="http://wiki.developers.facebook.com/index.php/Admin.getAppProperties">
  Developers Wiki: Admin.getAppProperties</a>