title: Missing return type in uml class
body: <p>I have to write the java code corresponding the following class diagram:
  <a href="https://i.stack.imgur.com/igofU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/igofU.png" alt="enter image description here"></a></p>
  
  <p>what about missing informations about visibility and return type of methods? Is the visibility understood as 'package'? Is the return type understood as 'void'?</p>