docs: private String getCommonAncestorPath(String rootPath1, String rootPath2) {
  
          if (rootPath1 == null) {
              return rootPath2;
          }
          if (rootPath2 == null) {
              return rootPath1;
          }
          rootPath1 = CmsStringUtil.joinPaths("/", rootPath1, "/");
          rootPath2 = CmsStringUtil.joinPaths("/", rootPath2, "/");
          int minLength = Math.min(rootPath1.length(), rootPath2.length());
          int i;
          for (i = 0; i < minLength; i++) {
              char char1 = rootPath1.charAt(i);
              char char2 = rootPath2.charAt(i);
              if (char1 != char2) {
                  break;
              }
          }
          String result = rootPath1.substring(0, i);
          if ("/".equals(result)) {
              return result;
          }
          int slashIndex = result.lastIndexOf('/');
          result = result.substring(0, slashIndex);
          return result;
      }