private boolean isPreflightRequest(HttpServletRequest httpReq) {
        return isOptionsMethod(httpReq) && hasOriginHeader(httpReq);
    }
Determines whether the request is a CORS preflight request.
@param httpReq the http servlet request
@return true if preflight, else false
common/servlet/src/main/java/io/apiman/common/servlet/ApimanCorsFilter.java