code: static <T extends ChronoEntity<T>> ElementRule<T, Integer> elementRule(Class<T> type) {
  
          return new ERule<>();
  
      }
docs: <p>Erzeugt eine Elementregel. </p>
  
  @param   <T> either {@code PlainDate} or {@code PlainTimestamp}
  @param   type    helps to improve type inference
  @return  new element rule