code: public static void assertRequestReceived(String method, long sequenceNumber, MessageListener obj) {
      assertRequestReceived(null, method, sequenceNumber, obj);
    }
docs: Asserts that the given message listener object received a request with the indicated CSeq
  method and CSeq sequence number.
  
  @param method The CSeq method to look for (SipRequest.REGISTER, etc.)
  @param sequenceNumber The CSeq sequence number to look for
  @param obj The MessageListener object (ie, SipCall, Subscription, etc.).