title: Clean architecture - where to put input validation logic?
body: <p>Perhaps in the app I have a feature allowing users to send feedback using a form with some validation logic:</p>
  
  <ul>
  <li>name can be empty</li>
  <li>feedback message should be at least 5 characters</li>
  </ul>
  
  <p>Where would you put these validation logic, either in <code>domain layer</code> as business logic or in <code>presentation layer</code> as UI logic?</p>
  
  <p>These logic are applied for all applications (android, iOS, web). Please note that we already had server side validation.</p>