title: Java 8 date-time: get start of day from ZonedDateTime
body: <p>Is there any difference between these:</p>
  
  <pre><code>zonedDateTime.truncatedTo(ChronoUnit.DAYS);
  
  zonedDateTime.toLocalDate().atStartOfDay(zonedDateTime.getZone());
  </code></pre>
  
  <p>Any reason to prefer one against the other?</p>
  
  <p>Thanks</p>