    pub adapter: A,
    /// Value retrieved from cache.
    pub result: CachedValue<T>,
}

/// Required `Debug` implementation to use `instrument` macro.
impl<A, T> fmt::Debug for CachePolledStale<A, T>
where
    A: RuntimeAdapter,
    T: CacheableResponse,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str("CachePolledStale")
    }