@Override
    default RequestContext unwrap() {
        return (RequestContext) Unwrappable.super.unwrap();
    }
Returns the hook which is invoked whenever this {@link RequestContext} is pushed to the
{@link RequestContextStorage}. The {@link SafeCloseable} returned by the {@link Supplier} will be
called whenever this {@link RequestContext} is popped from the {@link RequestContextStorage}.
core/src/main/java/com/linecorp/armeria/common/RequestContext.java