title: How to specify a default value for a boolean field using MapStruct
body: <p>How can you specify a <code>defaultValue</code> when mapping a DTO using MapStruct? The following constructs did not work</p>
  
  <pre><code>@Mapping(target = "used", defaultValue = "0")
  MyDTO toDto(MyEntity entity);
  
  @Mapping(target = "used", defaultValue = "false")
  MyDTO toDto(MyEntity entity);
  </code></pre>
  
  <p>The documentation shows examples for all types except booleans</p>