code: public boolean isSupported()
                      throws NoResponseException, XMPPErrorException, NotConnectedException, InterruptedException {
          return ServiceDiscoveryManager.getInstanceFor(connection()).accountSupportsFeatures(
                          PushNotificationsElements.NAMESPACE);
      }
docs: Returns true if Push Notifications are supported by this account.
  
  @return true if Push Notifications are supported by this account.
  @throws NoResponseException
  @throws XMPPErrorException
  @throws NotConnectedException
  @throws InterruptedException
  @since 4.2.2