code: public Page getRelativePage(String relativePath) {
      String path = getRootPath();
      if (path == null) {
        return null;
      }
      StringBuilder sb = new StringBuilder(path);
      if (!relativePath.startsWith("/")) {
        sb.append("/");
      }
      sb.append(relativePath);
      return pageManager.getPage(sb.toString());
    }
docs: Get page relative to site root.
  @param relativePath Path relative to site root
  @return Page instance or null if not found