code: public List<Subscription> getSubscriptions(List<ExtensionElement> additionalExtensions, Collection<ExtensionElement> returnedExtensions)
                      throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
          return getSubscriptions(SubscriptionsNamespace.basic, additionalExtensions, returnedExtensions);
      }
docs: Get the subscriptions currently associated with this node.
  <p>
  {@code additionalExtensions} can be used e.g. to add a "Result Set Management" extension.
  {@code returnedExtensions} will be filled with the stanza extensions found in the answer.
  </p>
  
  @param additionalExtensions
  @param returnedExtensions a collection that will be filled with the returned packet
  extensions
  @return List of {@link Subscription}
  @throws NoResponseException
  @throws XMPPErrorException
  @throws NotConnectedException
  @throws InterruptedException