Private cache key

Key.java

    private static class Key {

        private final Object key;
        private final long timelife;

        public Key(Object key, long timeout) {
            this.key = key;
            this.timelife = System.currentTimeMillis() + TimeUnit.SECONDS.toMillis(timeout);
        }

        public Key(Object key) {
            this.key = key;
            this.timelife = TimeUnit.SECONDS.toMillis(300L);
        }

        public Object getKey() {
            return key;
        }

        public boolean isLive(long currentTimeMillis) {
            return currentTimeMillis < timelife;
        }

        @Override
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            final Key other = (Key) obj;
            if (this.key != other.key && (this.key == null || !this.key.equals(other.key))) {
                return false;
            }
            return true;
        }

        @Override
        public int hashCode() {
            int hash = 7;
            hash = 43 * hash + (this.key != null ? this.key.hashCode() : 0);
            return hash;
        }

        @Override
        public String toString() {
            return "Key{" + "key=" + key + '}';
        }
    }