NullPointerException : Cannot provide charset MediaType with application/json

The following REST service generate a NullPointerException when calling /test/bug

package mytest;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;

@Path("/test")
public class TestService {
@GET
@Path("bug")
@Produces(

{"application/json;charset=UTF-8"}

)
public MyObject bug()

{ return new MyObject(); }

@GET
@Path("nobug")
@Produces({"application/json"})
public MyObject nobug() { return new MyObject(); }

}

Exception:

java.lang.NullPointerException
org.jboss.resteasy.plugins.providers.jaxb.BaseMarshaller.setProperty(BaseMarshaller.java:35)
org.jboss.resteasy.plugins.providers.jaxb.AbstractJAXBProvider.setCharset(AbstractJAXBProvider.java:141)
org.jboss.resteasy.plugins.providers.jaxb.AbstractJAXBProvider.getMarshaller(AbstractJAXBProvider.java:118)
org.jboss.resteasy.plugins.providers.jaxb.AbstractJAXBProvider.writeTo(AbstractJAXBProvider.java:92)
org.jboss.resteasy.core.interception.MessageBodyWriterContextImpl.proceed(MessageBodyWriterContextImpl.java:114)
org.jboss.resteasy.plugins.interceptors.encoding.GZIPEncodingInterceptor.write(GZIPEncodingInterceptor.java:46)
org.jboss.resteasy.core.interception.MessageBodyWriterContextImpl.proceed(MessageBodyWriterContextImpl.java:120)
org.jboss.resteasy.core.ServerResponse.writeTo(ServerResponse.java:184)
org.jboss.resteasy.core.SynchronousDispatcher.writeJaxrsResponse(SynchronousDispatcher.java:413)
org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:376)
org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:160)
org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:113)
org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:69)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)