title: Does Vaadin 8 `Binder::bindInstanceFields` only work with String data types?
body: <p>Using the <a href="http://www.Vaadin.com/" rel="noreferrer">Vaadin</a> 8 <a href="https://vaadin.com/api/8.0.5/com/vaadin/annotations/PropertyId.html" rel="noreferrer"><code>@PropertyId</code></a> annotation with the <a href="https://vaadin.com/api/8.0.5/com/vaadin/data/Binder.html#bindInstanceFields-java.lang.Object-" rel="noreferrer"><code>Binder::bindInstanceFields</code></a> is certainly shorter and sweeter than writing a line of code for each field-property binding.</p>
  <pre><code>Person person;  // `name` is String, `yearOfBirth` is Integer.
  …
  @PropertyId ( &quot;name&quot; )
  final TextField nameField = new TextField ( &quot;Full name:&quot; ); // Bean property.
  
  @PropertyId ( &quot;yearOfBirth&quot; )
  final TextField yearOfBirthField = new TextField ( &quot;Year of Birth:&quot; ); // Bean property.
  …
  // Binding
  Binder &lt; Person &gt; binder = new Binder &lt;&gt; ( Person.class );
  binder.bindInstanceFields ( this );
  binder.setBean ( person );
  </code></pre>
  <p>But we get an Exception thrown because the <code>yearOfBirth</code> property is an Integer, and this easy-does-it binding approach lacks an converter.</p>
  <blockquote>
  <p>SEVERE:</p>
  <p>java.lang.IllegalStateException: Property type 'java.lang.Integer' doesn't match the field type 'java.lang.String'. Binding should be configured manually using converter.</p>
  </blockquote>
  <p>Does that mean <a href="https://vaadin.com/api/8.0.5/com/vaadin/data/Binder.html#bindInstanceFields-java.lang.Object-" rel="noreferrer"><code>Binder::bindInstanceFields</code></a> can be used only a beans made entirely of properties of <code>String</code> data type?</p>
  <p>Is there a way to specify a <a href="https://vaadin.com/api/8.0.5/com/vaadin/data/Converter.html" rel="noreferrer"><code>Converter</code></a> such as <a href="https://vaadin.com/api/8.0.5/com/vaadin/data/converter/StringToIntegerConverter.html" rel="noreferrer"><code>StringToIntegerConverter</code></a> without having to itemize each and every binding in code?</p>