code: @Override
    public Set<Map.Entry<String, Object>> entrySet() {
      Set<Map.Entry<String, Object>> entrySet = getDecoratee().entrySet();
      Map<String, Object> result = new HashMap<>();
      for (Map.Entry<String, Object> entry : entrySet) {
        if ("regexp".equals(entry.getKey())) {
          result.put("value", javaToJavaScriptRegexpPattern(entry));
        } else {
          result.put(entry.getKey(), entry.getValue());
        }
      }
      return result.entrySet();
    }
docs: Modifies the original entry set such that the value for the 'regexp' attribute is a JavaScript regexp pattern.
  The following transformations are applied:
  <ul>
  <li>adding '/' prefix and suffix turning a Java pattern like "abc" into "/abc/" for JavaScript</li>
  </ul>
  Furthermore, the 'regexp' attribute is renamed to 'value' because that's what valdr expects.
  
  @return the modified entry set