code: public static void assertHeaderPresent(String msg, SipMessage sipMessage, String header) {
      assertNotNull("Null assert object passed in", sipMessage);
      assertTrue(msg, sipMessage.getHeaders(header).hasNext());
    }
docs: Asserts that the given SIP message contains at least one occurrence of the specified header.
  Assertion failure output includes the given message text.
  
  @param msg message text to output if the assertion fails.
  @param sipMessage the SIP message.
  @param header the string identifying the header as specified in RFC-3261.