code: private String getElementID(final String relativePath) {
          final String fragment = getFragment(relativePath);
          if (fragment != null) {
              if (fragment.lastIndexOf(SLASH) != -1) {
                  return fragment.substring(fragment.lastIndexOf(SLASH) + 1);
              } else {
                  return fragment;
              }
          }
          return null;
      }
docs: Retrieve the element ID from the path. If there is no element ID, return topic ID.