code: public String getId() {
          if (id == null) {
              if (isValid()) {
                  id = getProperty(ResourceUtil.PROP_UUID);
              }
              if (StringUtils.isBlank(id)) {
                  id = Base64.encodeBase64String(getPath().getBytes(MappingRules.CHARSET));
              }
          }
          return id;
      }
docs: Lazy getter for the ID of the resources. The ID is the UUID of the resources node if available otherwise the
  Base64 encoded path.
  
  @return a hopefully useful ID (not <code>null</code>)