title: Mapstruct LocalDateTime to Instant
body: <p>I am new in Mapstruct. I have a model object which includes <code>LocalDateTime</code> type field. DTO includes <code>Instant</code> type field. I want to map <code>LocalDateTime</code> type field to <code>Instant</code> type field. I have <strong>TimeZone</strong> instance of incoming requests.</p>
  
  <p>Manually field setting like that;</p>
  
  <pre><code>set( LocalDateTime.ofInstant(x.getStartDate(), timeZone.toZoneId()) )
  </code></pre>
  
  <p>How can I map these fields using with Mapstruct?</p>