code: public static void assertResponseReceived(int statusCode, String method, long sequenceNumber,
        MessageListener obj) {
      assertResponseReceived(null, statusCode, method, sequenceNumber, obj);
    }
docs: Asserts that the given message listener object received a response with the indicated status
  code, CSeq method and CSeq sequence number.
  
  @param statusCode The response status code to check for (eg, SipResponse.RINGING)
  @param method The CSeq method to look for (SipRequest.INVITE, etc.)
  @param sequenceNumber The CSeq sequence number to look for
  @param obj The MessageListener object (ie, SipCall, Subscription, etc.).