Update Minecraft server configuration with new JVM options and properties

nix-system-configs/modules/system/minecraft.nix

@@ -78,8 +78,26 @@ in {
         package = pkgs.neoforgeServers.neoforge-1_21_1-21_1_224;
 
         jvmOpts = lib.concatStringsSep " " [
-          "-Xms18G"
+          "-Xms4G"
           "-Xmx45G"
+          "-XX:+UseG1GC
+           -XX:+ParallelRefProcEnabled
+           -XX:MaxGCPauseMillis=200
+           -XX:+UnlockExperimentalVMOptions
+           -XX:+DisableExplicitGC
+           -XX:+AlwaysPreTouch
+           -XX:G1NewSizePercent=30
+           -XX:G1MaxNewSizePercent=40
+           -XX:G1HeapRegionSize=8M
+           -XX:G1ReservePercent=20
+           -XX:G1HeapWastePercent=5
+           -XX:G1MixedGCCountTarget=4
+           -XX:InitiatingHeapOccupancyPercent=15
+           -XX:G1MixedGCLiveThresholdPercent=90
+           -XX:G1RSetUpdatingPauseTimePercent=5
+           -XX:SurvivorRatio=32
+           -XX:+PerfDisableSharedMem
+           -XX:MaxTenuringThreshold=1"
         ];
 
         serverProperties = {
@@ -97,7 +115,58 @@ in {
           enable-command-block = false;
           enable-rcon = false;
           require-resource-pack = false;
+          level-type = "minecraft:amplified";
           level-seed = "-2032795982907864146";
+
+          # Added properties (do not overwrite existing ones above)
+          accepts-transfers = false;
+          allow-flight = true;
+          allow-nether = true;
+          broadcast-console-to-ops = true;
+          broadcast-rcon-to-ops = true;
+          bug-report-link = "";
+          enable-jmx-monitoring = false;
+          enable-query = false;
+          enable-status = true;
+          enforce-whitelist = false;
+          entity-broadcast-range-percentage = 100;
+          force-gamemode = false;
+          function-permission-level = 2;
+          generate-structures = true;
+          generator-settings = {};
+          hardcore = false;
+          hide-online-players = false;
+          initial-disabled-packs = "";
+          initial-enabled-packs = "vanilla";
+          level-name = "world";
+          log-ips = true;
+          max-chained-neighbor-updates = 1000000;
+          max-tick-time = 180000;
+          max-world-size = 29999984;
+          network-compression-threshold = 256;
+          op-permission-level = 4;
+          player-idle-timeout = 0;
+          prevent-proxy-connections = false;
+          pvp = true;
+          # dotted keys must be quoted
+          "query.port" = 25566;
+          rate-limit = 0;
+          "rcon.password" = "";
+          "rcon.port" = 25575;
+          region-file-compression = "deflate";
+          resource-pack = "";
+          resource-pack-id = "";
+          resource-pack-prompt = "";
+          resource-pack-sha1 = "";
+          server-ip = "";
+          spawn-animals = true;
+          spawn-monsters = true;
+          spawn-npcs = true;
+          sync-chunk-writes = true;
+          text-filtering-config = "";
+          use-native-transport = true;
+          # white-list, view-distance, simulation-distance, spawn-protection, etc.
+          # were kept above to avoid overwriting existing values.
         };
 
         # Grant operator privileges to the user with the given UUID.
@@ -113,12 +182,17 @@ in {
         symlinks = {
           "mods" = "${modpack}/mods";
           "datapacks" = "${modpack}/datapacks";
+          "user_jvm_args.txt" = "${modpack}/user_jvm_args.txt";
         };
         files = {
           "config" = "${modpack}/config";
+          "patchouli_books" = "${modpack}/patchouli_books";
           "defaultconfigs" = "${modpack}/defaultconfigs";
           "kubejs" = "${modpack}/kubejs";
           "local" = "${modpack}/local";
+          ".mixin.out" = "${modpack}/.mixin.out";
+          "patchouli_books" = "${modpack}/patchouli_books";
+          "dynamic-data-pack-cache" = "${modpack}/dynamic-data-pack-cache";
         };
       };
 
@@ -417,10 +491,32 @@ in {
       };
     };
 
-    # For FastBackup force etc to have PATH
+    # For FastBackup and to force OpenJDK 21 for the Minecraft services,
+    # set JAVA_HOME and include the OpenJDK bin in the service environment.
+    # Add matching environment for both server units created by nix-minecraft.
     systemd.services."minecraft-server-fabric-modded".environment = {
+      JAVA_HOME = lib.mkForce "${pkgs.openjdk21}";
       PATH = lib.mkForce (
         lib.makeBinPath [
+          pkgs.openjdk21
+          pkgs.git
+          pkgs.git-lfs
+          pkgs.coreutils
+          pkgs.findutils
+          pkgs.gnugrep
+          pkgs.gnused
+          pkgs.systemd
+        ]
+        + ":/run/current-system/sw/bin"
+      );
+    };
+
+    # Ensure the other server unit also uses OpenJDK 21
+    systemd.services."minecraft-server-all-the-mods-tss".environment = {
+      JAVA_HOME = lib.mkForce "${pkgs.openjdk21}";
+      PATH = lib.mkForce (
+        lib.makeBinPath [
+          pkgs.openjdk21
           pkgs.git
           pkgs.git-lfs
           pkgs.coreutils