darwin: Merge shared configuration between hosts

hosts/darwin/shared/java.nix

@@ -0,0 +1,30 @@
+{ pkgs, ... }: {
+  # Install the latest JDK, and latest LTS JDK.
+  # Per https://github.com/LnL7/nix-darwin/issues/663,
+  # nix-darwin only supports a few specific named activation scripts.
+  # We'll leverage `extraActivation` to symlink our JDKs.
+  # TODO(spotlightishere): Migrate to explicit scripts when possible
+  system.activationScripts.extraActivation.text = ''
+    ##############
+    # Latest JDK #
+    ##############
+    # Regardless of version, we'd like the latest JDK available.
+
+    # Remove the symlink if it doesn't already exist.
+    rm -f /Library/Java/JavaVirtualMachines/zulu-latest.jdk
+
+    # We should only have a single JDK present within our package,
+    # but let's limit `find` regardless.
+    JDK_LOCATION="$(find "${pkgs.jdk24}" -name "*.jdk" | head -n1)"
+
+    # Symlink!
+    ln -sf "$JDK_LOCATION" "/Library/Java/JavaVirtualMachines/zulu-latest.jdk"
+
+    ##########
+    # JDK 21 #
+    ##########
+    # We'd also like the latest LTS version of the JDK available.
+    rm -f /Library/Java/JavaVirtualMachines/zulu-21.jdk
+    ln -sf "${pkgs.jdk21}/zulu-21.jdk" "/Library/Java/JavaVirtualMachines/zulu-21.jdk"
+  '';
+}