Java Webstart NixOS 18.09

This doesn’t seem any more manual than using any other restricted-license software via nix. I don’t think this is deprecated.

You’re right that 8u281 is not the latest, and indeed it doesn’t seem to be easy to find that download or Oracle’s site (probably intentionally, they want everyone using the latest patch version).

Anyway, if you want to pursue this, you can start by looking at the part of pkgs/top-level/all-packages.nix that defines jre8Plugin:

  jrePlugin = jre8Plugin;

  jre8Plugin = lowPrio (oraclejdk8distro false true);

  jdkdistro = oraclejdk8distro;

  oraclejdk8distro = installjdk: pluginSupport:
    (callPackage ../development/compilers/oraclejdk/jdk8-linux.nix {
      inherit installjdk pluginSupport;
    });

Then you can take a look at the history of jdk8-linux.nix to see what kind of update you’d need to make to get it up to a current version. The last two were: