Re: Still stuck on Java 8
There's a two part solution to that (AKA this works for me, YMMV):
1) Amazon Corretto 8 (32 and 64 bit flavours), fetched from Amazon or Ninite.
2) OpenWebStart by Karakun (https://www.openwebstart.com/download).
Now, you have to get into the OpenWebStart JVM manager settings, and point it to the appropriate Corretto binary (usually the Find Local button), and then go into the JVM manager settings and say, "Yes, I really want to use Amazon over Zulu or AdoptOpenJDK". As for why Corretto? It works, where AdoptOpenJDK and Zulu do not at all.
Once that's done, your Java 7/8 jnlp legacy app will work again. I've also tried our enterprise JNLPs against Corretto 11, and it also works ... somewhat ... until the under-updated 3rd party library gets involved, then it's fireballs (Java exceptions) all over the place.
edit: OWS clarifications