code: public static void assertBodyNotContains(String msg, SipMessage sipMessage, String value) {
      assertNotNull("Null assert object passed in", sipMessage);
      if (sipMessage.getContentLength() > 0) {
        String body = new String(sipMessage.getRawContent());
  
        if (body.indexOf(value) != -1) {
          fail(msg);
        }
      }
  
      assertTrue(true);
    }
docs: Asserts that the body in the given SIP message does not contain the value given, or that there
  is no body in the message. The assertion fails if the body is present and contains the value.
  Assertion failure output includes the given message text.
  
  @param msg message text to output if the assertion fails.
  @param sipMessage the SIP message.
  @param value the string value to look for in the body. An exact string match is done against
  the entire contents of the body. The assertion will fail if any part of the body matches
  the value given.