code: public static List<String> getPropertiesMatching(Predicate<? super String> matcher) {
        if (matcher != null) {
           return getInstance().properties.keySet().parallelStream().filter(matcher).collect(Collectors.toList());
        }
        return Collections.emptyList();
     }
docs: <p> Gets a <code>list</code> of properties whose name is matched using the supplied <code>StringMatcher</code>.
  </p>
  
  @param matcher The <code>StringMatcher</code> to use for matching property names.
  @return A <code>List</code> of properties matched using the <code>StringMatcher</code>.