code: private URI handleLocalHref(final URI attValue) {
          final URI current = new File(dirPath, filePath).toURI().normalize();
          final URI reference = current.resolve(attValue);
          final URI merge = output.toURI();
          return getRelativePath(merge, reference);
      }
docs: Rewrite local non-DITA href value.
  
  @param attValue href attribute value
  @return rewritten href value