Dont load the same addon twice

Author: TBlueF

common/src/main/java/de/bluecolored/bluemap/common/addons/AddonLoader.java

@@ -145,6 +145,7 @@ private synchronized void loadAddon(Addon addon) throws ConfigurationException {
         AddonInfo addonInfo = addon.getAddonInfo();
         Path jarFile = addon.getJarFile();
 
+        if (loadedAddons.containsKey(addonInfo.getId())) return;
         Logger.global.logInfo("Loading BlueMap Addon: %s (%s)".formatted(addonInfo.getId(), jarFile));
 
         try {