Add extension update folder

core/src/main/java/org/geysermc/geyser/extension/GeyserExtensionLoader.java

@@ -164,7 +164,34 @@ protected void loadAllExtensions(@NonNull ExtensionManager extensionManager) {
             Map<String, GeyserExtensionContainer> loadedExtensions = new LinkedHashMap<>();
 
             Pattern[] extensionFilters = this.extensionFilters();
-            List<Path> extensionPaths = Files.walk(extensionsDirectory).toList();
+
+            Path updateDirectory = extensionsDirectory.resolve("update");
+            if (Files.isDirectory(updateDirectory)) {
+                List<Path> extensionUpdatePaths = Files.list(updateDirectory).toList();
+                extensionUpdatePaths.forEach(path -> {
+                    if (Files.isDirectory(path)) {
+                        return;
+                    }
+
+                    for (Pattern filter : extensionFilters) {
+                        if (!filter.matcher(path.getFileName().toString()).matches()) {
+                            return;
+                        }
+                    }
+
+                    try {
+                        // Try load the description, so we know it's a valid extension
+                        GeyserExtensionDescription description = this.extensionDescription(path);
+
+                        // Overwrite the extension with the new jar
+                        Files.move(path, extensionsDirectory.resolve(path.getFileName()), StandardCopyOption.REPLACE_EXISTING);
+                    } catch (Throwable e) {
+                        GeyserImpl.getInstance().getLogger().error(GeyserLocale.getLocaleStringLog("geyser.extensions.update.failed", path.getFileName()), e);
+                    }
+                });
+            }
+
+            List<Path> extensionPaths = Files.list(extensionsDirectory).toList();
             extensionPaths.forEach(path -> {
                 if (Files.isDirectory(path)) {
                     return;