Issue on Android Oreo

[ursusursus]

Hey, since android oreo https://developer.android.com/about/versions/oreo/android-8.0-changes

The system properties net.dns1, net.dns2, net.dns3, and net.dns4 are no longer available, a change that improves privacy on the platform.

This is a current workaround https://stackoverflow.com/a/48973823/1541188 is to replace ResolverConfig.findAndroid method with results of the DnsServersDetector.getServers, added to lserver list

This is unfortunate as library will need a dependency on android

[ibauersachs]

Please read the readme:
https://github.com/dnsjava/dnsjava/blob/master/README.md