public static Duration diff(Date start, Date end) {
		return fromMillis(end.getTime() - start.getTime());
	}
public static Duration diff ( Date start , Date end ) { return fromMillis ( end . getTime ( ) - start . getTime ( ) ) ; }
Builds a duration based on the difference between two dates.
@param start the start date
@param end the end date
@return the duration