title: Ignore fields only in json but not xml with jackson-dataformat-xml
body: <p>Using <code>Jackson</code> with the <code>jackson-dataformat-xml</code> module, I am able to serialize <code>POJO</code> to both <code>JSON</code> and <code>XML</code>.  There are a few fields (xml attributes) in my object that should only be serialized to <code>XML</code> but not <code>JSON</code>.  If I apply the <code>@JsonIgnore</code> annotation, the field is completely ignored even with <code>@JsonXMLProperty</code>.</p>
  <p>How can I ignore fields only in <code>JSON</code> but not <code>XML</code>?</p>