code: private static String generateTraceId(final HttpServletRequest request)
  	{
  		final String existing = request.getHeader(TracingConstants.HTTP_HEADER_CORRELATION_ID);
  
  		if (existing == null)
  			return SimpleId.alphanumeric(TRACE_ID_LENGTH);
  		else
  			return existing;
  	}
docs: Generates a trace id (or uses the existing trace id passed in from the requesting service)
  
  @param request
  
  @return