title: How to set default locale for Vaadin Flow (13/14) to German
body: <p>is there something like?:</p>
  <pre><code>public static final Locale APP_LOCALE = Locale.GERMAN;
  </code></pre>
  <p>Operating system and browser locale are all in German but Vaadin UI DatePicker and Core-Buttons are still English</p>
  <p>Translation or Internationalization is not intended.</p>
  <p>HTML-Source is show correct;</p>
  <pre><code>&lt;!doctype html&gt;&lt;html lang=&quot;de&quot;&gt;
  </code></pre>
  <p>Resources I found are all very old and do not work for Vaadin Flow</p>
  <p>Thanks for any advice!</p>