title: Scene.getStylesheets().add() not working inside jar file
body: <p>As long as I run my project directly from Eclipse, I have no problem with that:</p>
  
  <pre><code>scene.getStylesheets().add(getClass().getResource("/stylesheet.css").toExternalForm());
  </code></pre>
  
  <p>But as soon as I run this code inside of a jar file, the resource is not found (<code>NullPointerException</code>).</p>
  
  <p>I tried moving the <code>css</code> file to my <code>src</code> folder and then only <code>stylesheet.css</code>as path instead of <code>/stylesheet.css</code>, but this leads to the same problem: Works fine using Eclipse, but not from the jar.</p>
  
  <p><strong>Hint</strong>: I am using <a href="https://github.com/zonski/javafx-maven-plugin/wiki" rel="noreferrer">Zonskis Maven JavaFX Plugin</a> for generating the jar.</p>