title: Adding new line in error-message for vaadin form validation
body: <p>I have a form fields binded to java entity model. That model has an annotation:</p>
  <pre><code>@ValidPassword
  private String password
  </code></pre>
  <p>which validates the field with some conditions and return error message containing each failed condition separated by '\n' new line sign.</p>
  <p>Vaadin form is connected to this model with:</p>
  <pre><code>    username =  new TextField(&quot;Username&quot;);
      username.addClassName(&quot;username-field&quot;);
      password =  new PasswordField(&quot;Password&quot;);
      password.addClassName(&quot;password-field&quot;);
      binder.forField(username ).asRequired().bind(&quot;username&quot;);
      binder.forField(password).asRequired().bind(&quot;password&quot;);
  </code></pre>
  <p>Writting input to password field results in:
  <a href="https://i.stack.imgur.com/QcPJ3.png" rel="nofollow noreferrer">image-link</a>
  When I want each failed condition to start on a new line.</p>