title: Vaadin TextField show validation error without hovering over error indicator
body: <p>I have added a validator to a vaadin text field.</p>
  
  <pre><code>usernameField.addValidator(value -&gt; {
      if (value.toString().trim().isEmpty()) {
          throw new Validator.InvalidValueException("Please enter your username");
      }
  });
  </code></pre>
  
  <p>And when user clicks a button, I call validate.</p>
  
  <pre><code>try {
      usernameField.validate();
  } catch (Validator.InvalidValueException e) {
      usernameField.setValidationVisible(true);
      return;
  }
  </code></pre>
  
  <p>When validation fails, vaadin adds an error indicator exclamation mark next to the text field. If I hover over this, the error message <code>"Please enter your username"</code> appears as a tooltip.</p>
  
  <p>I need to make the error message visible on the UI, without hovering over the error indicator.</p>
  
  <p>Is there a way to do this without using an additional error message label?</p>