code: public Object get(String hostname, int netId) {
          AddressCacheEntry entry = cache.get(new AddressCacheKey(hostname, netId));
          // Do we have a valid cache entry?
          if (entry != null && entry.expiryNanos >= System.nanoTime()) {
              return entry.value;
          }
          // Either we didn't find anything, or it had expired.
          // No need to remove expired entries: the caller will provide a replacement shortly.
          return null;
      }
docs: Returns the cached InetAddress[] for 'hostname' on network 'netId'. Returns null
  if nothing is known about 'hostname'. Returns a String suitable for use as an
  UnknownHostException detail message if 'hostname' is known not to exist.