Spring Boot Guava CacheMetrics

import com.google.common.cache.Cache;
import com.google.common.cache.CacheStats;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.actuate.endpoint.PublicMetrics;
import org.springframework.boot.actuate.metrics.Metric;
import org.springframework.cache.CacheManager;
import org.springframework.stereotype.Component;
import org.springframework.util.Assert;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.List;

@Component
public class CacheMetrics implements PublicMetrics {

    private CacheManager cacheManager;

    @Autowired
    public CacheMetrics(CacheManager cacheManager) {
        Assert.notNull(cacheManager, "cacheManager must not be null");
        this.cacheManager = cacheManager;
    }

    @Override
    public Collection<Metric<?>> metrics() {
        Collection<Metric<?>> result = new LinkedHashSet<>();
        List<String> cacheNames = new ArrayList<>(cacheManager.getCacheNames());
        Collections.sort(cacheNames); // sort cache names alphabetically
        for (String cacheName : cacheNames) {
            String prefix = String.format("cache.%s.", cacheName);
            Object nativeCache = cacheManager.getCache(cacheName).getNativeCache();
            if (nativeCache instanceof Cache) {
                Cache cache = (Cache) nativeCache;
                CacheStats stats = cache.stats();
                result.add(new Metric<>(prefix + "size", cache.size()));
                result.add(new Metric<>(prefix + "eviction_count", stats.evictionCount()));
                result.add(new Metric<>(prefix + "hit_count", stats.hitCount()));
                result.add(new Metric<>(prefix + "hit_rate", stats.hitRate()));
                result.add(new Metric<>(prefix + "miss_count", stats.missCount()));
                result.add(new Metric<>(prefix + "miss_rate", stats.missRate()));
                result.add(new Metric<>(prefix + "request_count", stats.requestCount()));
            }
        }
        return result;
    }
}