How to suppress the XML header in a JAX-RS Web Service in JBoss EAP 6?

Issue

I have a JAX-RS service deployed in JBoss EAP 6 and I want to remove the XML header when returning XML payload:

JAX-RS resource:

    @GET
    @Produces(MediaType.TEXT_XML)
    public MyObject doSomething();

Where MyObject has:

@XmlRootElement (name = "myObject")
public class MyObject {
}

The response is:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<myObject>...

I want to remove the following part:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>

How can I achieve that?