code: public String getUrlForPageReference(String pageReference) {
          String url = pageReferenceToPageUrlMap.get(pageReference);
          if (url == null) {
              fail("No url is found for page name: '" + pageReference + "'. Available page references are: " + pageReferenceToPageUrlMap.keySet().toString());
          }
          return url;
      }
docs: Find a {@link String} url by its reference name
  @param pageReference
  @return {@link String} representing the url to the page mapped to the passed in page name