code: public void requestDeviceListUpdateFor(BareJid contact)
              throws InterruptedException, PubSubException.NotALeafNodeException, XMPPException.XMPPErrorException,
              SmackException.NotConnectedException, SmackException.NoResponseException {
          synchronized (LOCK) {
              getOmemoService().refreshDeviceList(connection(), getOwnDevice(), contact);
          }
      }
docs: Request a deviceList update from contact contact.
  
  @param contact contact we want to obtain the deviceList from.
  @throws InterruptedException
  @throws PubSubException.NotALeafNodeException
  @throws XMPPException.XMPPErrorException
  @throws SmackException.NotConnectedException
  @throws SmackException.NoResponseException