code: public void unblockContacts(List<Jid> jids)
              throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
          UnblockContactsIQ unblockContactIQ = new UnblockContactsIQ(jids);
          connection().createStanzaCollectorAndSend(unblockContactIQ).nextResultOrThrow();
      }
docs: Unblock contacts.
  
  @param jids
  @throws NoResponseException
  @throws XMPPErrorException
  @throws NotConnectedException
  @throws InterruptedException