private void internalNext() {
            final Bytes cacheKey = keys.next();
            final LRUCacheEntry entry = cache.get(cacheKey);
            if (entry == null) {
                return;
            }

            nextEntry = new KeyValue<>(cacheKey, entry);
        }
Add a listener that is called each time an entry is evicted from the cache or an explicit flush is called
streams/src/main/java/org/apache/kafka/streams/state/internals/ThreadCache.java