ConfigResponse get(ConfigCacheKey key) {
        PayloadChecksum xxhash64 = checksums.get(key);
        if (xxhash64 == null) return null;
        return checksumToConfig.get(xxhash64);
    }
Cache that holds configs and config definitions (builtin and user config definitions).

@author vegardh
configserver/src/main/java/com/yahoo/vespa/config/server/ServerCache.java