Unable to get DNS data in restricted network, no public function to customize Netty's DNS

I'm using Pushy 0.15.2, and I have encounted `UnknownHostException: Failed to resolve 'api.push.apple.com' after 2 queries` errors in restricted network. After some investigation, it turn out that Netty cannot use `sun.net.dns.ResolverConfiguration` correctly on Java 17, forced it fallback to use Google DNS instead of local DNS server. Asked Netty's dev and told me that I can specify the dns servers to use when creating the `DnsNameResolver` via `DnsNameServerBuilder`. Since it will be deployed onto restricted network which doesn't allow to use public DNS, so this is a MUST choose.

Since it is hidden deep inside the Pushy and I don't think I see there's any public function from Pushy that I can input a `DnsNameResolver` object. So I want to ask if there's anyway to do this without fiddling Pushy's source code?