Thank you, Tomas. Yeah, your post helped.

And below is my code, may be it helps to some developers:

public class SubscribeComposer extends RESTEasyMessageComposer {


    private Logger LOG = LoggerFactory.getLogger(this.getClass().getName());
    public String stan;
    public String project;
    public String name;


    @Override
    public Message compose(RESTEasyBindingData source, Exchange exchange) throws Exception {
        Message target = super.compose(source, exchange);
        kz.atf.types.SubscribeRqu rqu = target.getContent(kz.atf.types.SubscribeRqu.class);
        stan = rqu.getMethod().getStan();
        project = rqu.getMethod().getProject();
        name = rqu.getMethod().getName();
        return target;
    }


    @Override
    public RESTEasyBindingData decompose(Exchange exchange, RESTEasyBindingData target) throws Exception {
        LOG.info("state: " + exchange.getState());
        kz.atf.types.common.Response r = new kz.atf.types.common.Response<SubscribeRspParams>();
        SubscribeRspParams prm = new SubscribeRspParams();
        SubscribeRsp rsp = new SubscribeRsp();
        r.setStan(stan);
        r.setProject(project);
        r.setName(name);
        if (exchange.getContext().getProperty("exCaused") != null) {
            prm.setResponseCode("-1");
            prm.setStatus((String) exchange.getContext().getProperty("exCaused").getValue());
        } else {
            if (exchange.getState().equals(ExchangeState.FAULT)) {
                if (exchange.getMessage().getContent() instanceof HandlerException) {
                    if (exchange.getMessage().getContent(String.class).contains("XmlValidator")) {
                        HandlerException he = exchange.getMessage().getContent(HandlerException.class);
                        String message = he.getMessage().substring(he.getMessage().indexOf("SAXParseException"), he.getMessage().length());
                        prm.setResponseCode("-1");
                        prm.setStatus(message);
                        r.setParameters(prm);
                        rsp.setMethod(r);
                        throw new WebApplicationException(
                                Response
                                .status(Response.Status.FORBIDDEN)
                                .entity(rsp)
                                .type(MediaType.TEXT_XML)
                                .build());
                    }
                }
            } else {
                prm.setResponseCode("00");
                prm.setStatus("OK");
            }
        }
        r.setParameters(prm);
        rsp.setMethod(r);
        exchange.getMessage().setContent(rsp);
        target = super.decompose(exchange, target);
        return target;
    }
}