code: public static void assertHeaderNotContains(SipMessage sipMessage, String header, String value) {
      assertHeaderNotContains(null, sipMessage, header, value);
    }
docs: Asserts that the given SIP message contains no occurrence of the specified header with the
  value given, or that there is no occurrence of the header in the message. The assertion fails
  if any occurrence of the header contains the value.
  
  @param sipMessage the SIP message.
  @param header the string identifying the header as specified in RFC-3261.
  @param value the string value within the header to look for. An exact string match is done
  against the entire contents of the header. The assertion will fail if any part of the
  header matches the value given.