Netflix/Hystrix

Hi. I'm using HystrixRequestVariableDefault for a variable that should be copied and shared between threads in the same request, and some times I get unexpectedly 'null' from calling get() on the variable. I found this weird since I initialize the HystrixRequestVariableDefault in the beginning of each request just after I do HystrixRequestContext.initializeContext(). Since this problem only occurs on some of the requests, and especially if I'm doing multiple requests at the same time, I would think that the problem is due to some data are not copied between threads. I am using my own implementation of HystrixConcurrencyStrategy where I override "wrapCallable" like this:

@Override
    public <K> Callable<K> wrapCallable(Callable<K> c) {
        HystrixRequestContext requestContext = HystrixRequestContext.getContextForCurrentThread();
        CallContextData foo = CallContext.getData();
        return () -> {
            HystrixRequestContext.setContextOnCurrentThread(requestContext);
            CallContext.setData(foo);
            return c.call();
        };
    }

CallContext contains a HystrixRequestVariableDefault<CallContextData> which is where I get the nullpointer when I'm calling get() on that other places in the code. Any ideas on what I'm doing wrong?