title: Formatting a Duration in Java 8 / jsr310
body: <p>I am transitioning a project from Joda-Time to java8's native time libraries, and I have run into a snag. </p>
  
  <p>I have been unable to find a formatter for Duration. I would like to have a custom String format of, for instance, <strong>HHH+MM</strong>, where a Duration of 75 hours and 15 minutes would format as <strong>"75+15"</strong>. </p>
  
  <p>This was easy to do with Joda-Time by converting to period, and using a PeriodFormatter, but I have been unable to find this type of class in Java8. Am I missing something?</p>