Fix loading multiple extensions (Closes #2826)

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

@@ -39,12 +39,13 @@ import java.util.Map;
 public class GeyserExtensionClassLoader extends URLClassLoader {
     private final GeyserExtensionLoader loader;
     private final Map<String, Class<?>> classes = new HashMap<>();
-    private final Extension extension;
 
-    public GeyserExtensionClassLoader(GeyserExtensionLoader loader, ClassLoader parent, ExtensionDescription description, Path path) throws InvalidExtensionException, MalformedURLException {
+    public GeyserExtensionClassLoader(GeyserExtensionLoader loader, ClassLoader parent, Path path) throws MalformedURLException {
         super(new URL[] { path.toUri().toURL() }, parent);
         this.loader = loader;
+    }
 
+    public Extension load(ExtensionDescription description) throws InvalidExtensionException {
         try {
             Class<?> jarClass;
             try {
@@ -57,10 +58,10 @@ public class GeyserExtensionClassLoader extends URLClassLoader {
             try {
                 extensionClass = jarClass.asSubclass(Extension.class);
             } catch (ClassCastException ex) {
-                throw new InvalidExtensionException("Main class " + description.main() + " should extends GeyserExtension, but extends " + jarClass.getSuperclass().getSimpleName(), ex);
+                throw new InvalidExtensionException("Main class " + description.main() + " should implement Extension, but extends " + jarClass.getSuperclass().getSimpleName(), ex);
             }
 
-            this.extension = extensionClass.getConstructor().newInstance();
+            return extensionClass.getConstructor().newInstance();
         } catch (IllegalAccessException | InvocationTargetException | NoSuchMethodException ex) {
             throw new InvalidExtensionException("No public constructor", ex);
         } catch (InstantiationException ex) {
@@ -77,6 +78,7 @@ public class GeyserExtensionClassLoader extends URLClassLoader {
         if (name.startsWith("org.geysermc.geyser.") || name.startsWith("net.minecraft.")) {
             throw new ClassNotFoundException(name);
         }
+
         Class<?> result = this.classes.get(name);
         if (result == null) {
             if (checkGlobal) {
@@ -94,8 +96,4 @@ public class GeyserExtensionClassLoader extends URLClassLoader {
         }
         return result;
     }
-
-    public Extension extension() {
-        return this.extension;
-    }
 }

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

@@ -78,13 +78,15 @@ public class GeyserExtensionLoader extends ExtensionLoader {
 
         final GeyserExtensionClassLoader loader;
         try {
-            loader = new GeyserExtensionClassLoader(this, getClass().getClassLoader(), description, path);
+            loader = new GeyserExtensionClassLoader(this, getClass().getClassLoader(), path);
         } catch (Throwable e) {
             throw new InvalidExtensionException(e);
         }
 
         this.classLoaders.put(description.name(), loader);
-        return this.setup(loader.extension(), description, dataFolder, new GeyserExtensionEventBus(GeyserImpl.getInstance().eventBus(), loader.extension()));
+
+        final Extension extension = loader.load(description);
+        return this.setup(extension, description, dataFolder, new GeyserExtensionEventBus(GeyserImpl.getInstance().eventBus(), extension));
     }
 
     private GeyserExtensionContainer setup(Extension extension, GeyserExtensionDescription description, Path dataFolder, ExtensionEventBus eventBus) {
@@ -110,10 +112,11 @@ public class GeyserExtensionLoader extends ExtensionLoader {
         Class<?> clazz = this.classes.get(name);
         try {
             for (GeyserExtensionClassLoader loader : this.classLoaders.values()) {
-                try {
+                if (clazz != null) {
-                    clazz = loader.findClass(name,false);
+                    continue;
-                } catch(NullPointerException ignored) {
                 }
+
+                clazz = loader.findClass(name, false);
             }
             return clazz;
         } catch (NullPointerException s) {