Persist pluginCommands across plugin restarts, compile velocity with jdk 11

Velocity/build.gradle

@@ -7,6 +7,8 @@ String dependencyDir = group + '.dependencies'
 version = rootProject.version
 archivesBaseName = rootProject.name + '-Velocity'
 
+sourceCompatibility = targetCompatibility = JavaVersion.VERSION_11
+
 repositories {
     maven { url 'https://nexus.velocitypowered.com/repository/maven-public/' }
     maven { url 'https://libraries.minecraft.net' }

Velocity/src/main/java/net/frankheijden/serverutils/velocity/ServerUtils.java

@@ -3,17 +3,16 @@ package net.frankheijden.serverutils.velocity;
 import co.aikar.commands.CommandCompletions;
 import co.aikar.commands.VelocityCommandCompletionContext;
 import co.aikar.commands.VelocityCommandManager;
-import com.google.common.collect.HashMultimap;
-import com.google.common.collect.Multimap;
-import com.google.common.collect.Multimaps;
 import com.google.inject.Inject;
 import com.google.inject.name.Named;
 import com.velocitypowered.api.event.Subscribe;
 import com.velocitypowered.api.event.proxy.ProxyInitializeEvent;
+import com.velocitypowered.api.event.proxy.ProxyShutdownEvent;
 import com.velocitypowered.api.plugin.Plugin;
 import com.velocitypowered.api.plugin.PluginContainer;
 import com.velocitypowered.api.plugin.annotation.DataDirectory;
 import com.velocitypowered.api.proxy.ProxyServer;
+import java.io.IOException;
 import java.nio.file.Path;
 import net.frankheijden.serverutils.common.ServerUtilsApp;
 import net.frankheijden.serverutils.common.config.Config;
@@ -21,6 +20,7 @@ import net.frankheijden.serverutils.common.config.Messenger;
 import net.frankheijden.serverutils.velocity.commands.CommandPlugins;
 import net.frankheijden.serverutils.velocity.commands.CommandServerUtils;
 import net.frankheijden.serverutils.velocity.entities.VelocityPlugin;
+import net.frankheijden.serverutils.velocity.managers.VelocityPluginCommandManager;
 import net.frankheijden.serverutils.velocity.managers.VelocityPluginManager;
 import net.frankheijden.serverutils.velocity.reflection.RVelocityCommandManager;
 import org.bstats.velocity.Metrics;
@@ -39,6 +39,7 @@ public class ServerUtils {
     private static ServerUtils instance;
     private static final String CONFIG_RESOURCE = "velocity-config.toml";
     private static final String MESSAGES_RESOURCE = "velocity-messages.toml";
+    private static final String PLUGIN_COMMANDS_CACHE = ".pluginCommandsCache.json";
 
     private VelocityPlugin plugin;
     private VelocityCommandManager commandManager;
@@ -60,17 +61,26 @@ public class ServerUtils {
     @Named("serverutils")
     private PluginContainer pluginContainer;
 
-    private final Multimap<String, String> pluginCommands = Multimaps.synchronizedSetMultimap(HashMultimap.create());
+    private final VelocityPluginCommandManager pluginCommandManager;
 
     /**
      * Initialises ServerUtils.
      */
     @Inject
-    public ServerUtils(ProxyServer proxy) {
+    public ServerUtils(ProxyServer proxy, @DataDirectory Path dataDirectory) {
+        try {
+            this.pluginCommandManager = VelocityPluginCommandManager.load(dataDirectory.resolve(PLUGIN_COMMANDS_CACHE));
+        } catch (IOException ex) {
+            throw new RuntimeException(ex);
+        }
+
         RVelocityCommandManager.proxyRegistrars(
                 proxy,
                 getClass().getClassLoader(),
-                (container, meta) -> pluginCommands.putAll(container.getDescription().getId(), meta.getAliases())
+                (container, meta) -> pluginCommandManager.getPluginCommands().putAll(
+                        container.getDescription().getId(),
+                        meta.getAliases()
+                )
         );
     }
 
@@ -102,6 +112,18 @@ public class ServerUtils {
         ServerUtilsApp.tryCheckForUpdates();
     }
 
+    /**
+     * De-initialises and disables ServerUtils.
+     */
+    @Subscribe
+    public void onDisable(ProxyShutdownEvent event) {
+        try {
+            pluginCommandManager.save();
+        } catch (IOException ex) {
+            ex.printStackTrace();
+        }
+    }
+
     public static ServerUtils getInstance() {
         return instance;
     }
@@ -126,8 +148,8 @@ public class ServerUtils {
         return plugin;
     }
 
-    public Multimap<String, String> getPluginCommands() {
-        return pluginCommands;
+    public VelocityPluginCommandManager getPluginCommandManager() {
+        return pluginCommandManager;
     }
 
     public void reload() {

Velocity/src/main/java/net/frankheijden/serverutils/velocity/managers/VelocityPluginCommandManager.java

@@ -0,0 +1,58 @@
+package net.frankheijden.serverutils.velocity.managers;
+
+import com.google.common.collect.HashMultimap;
+import com.google.common.collect.Multimap;
+import com.google.common.collect.Multimaps;
+import com.google.gson.Gson;
+import com.google.gson.reflect.TypeToken;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import java.util.Collection;
+import java.util.Map;
+
+public class VelocityPluginCommandManager {
+
+    private static final Gson gson = new Gson();
+
+    private final Multimap<String, String> pluginCommands;
+    private final Path path;
+
+    public VelocityPluginCommandManager(Path path) {
+        this.pluginCommands = Multimaps.synchronizedSetMultimap(HashMultimap.create());
+        this.path = path;
+    }
+
+    /**
+     * Loads and constructs a new {@link VelocityPluginCommandManager} from the given {@link Path}.
+     */
+    public static VelocityPluginCommandManager load(Path path) throws IOException {
+        var manager = new VelocityPluginCommandManager(path);
+        if (Files.exists(path)) {
+            Map<String, Collection<String>> rawMap = gson.fromJson(
+                    Files.newBufferedReader(path),
+                    new TypeToken<Map<String, Collection<String>>>(){}.getType()
+            );
+            rawMap.forEach(manager.pluginCommands::putAll);
+        }
+
+        return manager;
+    }
+
+    public Multimap<String, String> getPluginCommands() {
+        return pluginCommands;
+    }
+
+    /**
+     * Saves the map to the {@link Path} it was loaded from.
+     */
+    public void save() throws IOException {
+        Files.writeString(
+                path,
+                gson.toJson(pluginCommands.asMap()),
+                StandardOpenOption.CREATE,
+                StandardOpenOption.TRUNCATE_EXISTING
+        );
+    }
+}

Velocity/src/main/java/net/frankheijden/serverutils/velocity/managers/VelocityPluginManager.java

@@ -217,7 +217,8 @@ public class VelocityPluginManager extends AbstractPluginManager<PluginContainer
         }
 
         String pluginId = plugin.getDescription().getId();
-        for (String alias : ServerUtils.getInstance().getPluginCommands().removeAll(pluginId)) {
+        VelocityPluginCommandManager pluginCommandManager = ServerUtils.getInstance().getPluginCommandManager();
+        for (String alias : pluginCommandManager.getPluginCommands().removeAll(pluginId)) {
             proxy.getCommandManager().unregister(alias);
         }