@MustBeClosed
    public static SafeCloseable pop() {
        final RequestContext oldCtx = requestContextStorage.currentOrNull();
        if (oldCtx == null) {
            return noopSafeCloseable();
        }

        pop(oldCtx, null);
        return () -> requestContextStorage.push(oldCtx);
    }
Removes the {@link RequestContext} in the {@link RequestContextStorage} if exists and returns
{@link SafeCloseable} which pushes the {@link RequestContext} back to the {@link RequestContextStorage}.

<p>Because this method pops the {@link RequestContext} arbitrarily, it shouldn't be used in
most cases. One of the examples this can be used is in {@link ChannelFutureListener}.
The {@link ChannelFuture} can be complete when the eventloop handles the different request. The
eventloop might have the wrong {@link RequestContext} in the {@link RequestContextStorage},
so we should pop it.
core/src/main/java/com/linecorp/armeria/internal/common/RequestContextUtil.java