@Override
    public long getCacheMisses()
    {
        return cache.stats().missCount();
    }
Returns the number of cache misses. A cache miss occurs every
time the get method is called and the cache does not contain the
requested object.<p>
<p>
Keeping track of cache hits and misses lets one measure how efficient
the cache is; the higher the percentage of hits, the more efficient.

@return the number of cache hits.
xmppserver/src/main/java/org/jivesoftware/util/cache/CaffeineCache.java