docs: public String getServerPrefix(CmsObject cms, String resourceName) {
  
          if (resourceName.startsWith(cms.getRequestContext().getSiteRoot())) {
              // make sure this can also be used with a resource root path
              resourceName = resourceName.substring(cms.getRequestContext().getSiteRoot().length());
          }
          boolean secure = OpenCms.getStaticExportManager().isSecureLink(
              cms,
              resourceName,
              cms.getRequestContext().isSecureRequest());
  
          return (secure ? getSecureUrl() : getUrl());
      }