code: static <T extends Temporal<? super T>, I extends IsoInterval<T, I>> IntervalParser<T, I> of(
  		IntervalFactory<T, I> factory,
  		ChronoParser<T> parser,
  		BracketPolicy policy
  	) {
  
  		if (parser == null) {
  			throw new NullPointerException("Missing boundary parser.");
          }
  
  		return new IntervalParser<>(factory, parser, parser, policy, null);
  
  	}
docs: <p>Factory method with either solidus or hyphen as separation char. </p>
  
  @param   <T> generic temporal type
  @param   <I> generic interval type
  @param   factory         interval factory
  @param   parser          boundary parser
  @param   policy          bracket policy
  @return  new interval parser
  @since   2.0