ContextService (JSR236): transactional context always suspended

@WebService(serviceName = "Jsr236WebService")
@Stateless
public class Jsr236WebService {
    @Inject Jsr236ManagedTask jsr236ManagedTask;
    @Resource ManagedExecutorService executor;
    @Resource ContextService contextService;
 
    @WebMethod(operationName = "hello")
    public String hello(@WebParam(name = "name") String txt) {
        Map<String, String> execProps = new HashMap<>();
        execProps.put(ManagedTask.TRANSACTION, ManagedTask.USE_TRANSACTION_OF_EXECUTION_THREAD);
        Future<String> future = executor.submit(
                contextService.createContextualProxy(jsr236ManagedTask, execProps, Callable.class));

        try {
            return future.get();
        } catch (InterruptedException | ExecutionException e) {
            throw new RuntimeException(e);
        }
    }
}

@Dependent
@Transactional(Transactional.TxType.MANDATORY)
public class Jsr236ManagedTask implements Callable<String>, ManagedTask {
    @Override
    public String call() {
        return "called";
    }

    @Override
    public Map<String, String> getExecutionProperties() {
       Map<String, String> execProps = new HashMap<>();
        execProps.put(ManagedTask.TRANSACTION, ManagedTask.USE_TRANSACTION_OF_EXECUTION_THREAD);
        return execProps;
    }
}