Move away from using internal loader API

src/main/java/net/kyori/adventure/platform/fabric/FabricAudiences.java

@@ -160,7 +160,6 @@ static ResourceLocation toNative(final Key key) {
    * @param player the player to identify
    * @return an identified representation of the player
    * @since 4.0.0
-   *
    */
   static @NotNull Identified identified(final @NotNull Player player) {
     return (Identified) player;

src/main/java/net/kyori/adventure/platform/fabric/impl/AdventurePrelaunch.java

@@ -23,20 +23,53 @@
  */
 package net.kyori.adventure.platform.fabric.impl;
 
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.net.URL;
 import net.fabricmc.loader.api.entrypoint.PreLaunchEntrypoint;
-import net.fabricmc.loader.launch.common.FabricLauncherBase;
 
+/**
+ * Via i509VCB, a trick to get Brig onto the Knot classpath in order to properly mix in.
+ *
+ * <p>YOU SHOULD ONLY USE THIS CLASS DURING "preLaunch" and ONLY TARGET A CLASS WHICH IS NOT ANY CLASS YOU MIXIN TO.
+ * This will likely not work on Gson because FabricLoader has some special logic related to Gson.</p>
+ *
+ * <p>Original on GitHub at <a href="https://github.com/i509VCB/Fabric-Junkkyard/blob/ce278daa93804697c745a51af06ec812896ec2ad/src/main/java/me/i509/junkkyard/hacks/PreLaunchHacks.java">i509VCB/Fabric-Junkkyard</a></p>
+ */
 public class AdventurePrelaunch implements PreLaunchEntrypoint {
+  private static final ClassLoader KNOT_CLASSLOADER = Thread.currentThread().getContextClassLoader();
+  private static final Method ADD_URL_METHOD;
+
+  static {
+    try {
+      ADD_URL_METHOD = KNOT_CLASSLOADER.getClass().getMethod("addURL", URL.class);
+      ADD_URL_METHOD.setAccessible(true);
+    } catch (final ReflectiveOperationException ex) {
+      throw new RuntimeException("Failed to load Classloader fields", ex);
+    }
+  }
+
   @Override
   public void onPreLaunch() {
-    // TODO: Actually fix loader
-    final URL target;
     try {
-      target = Class.forName("com.mojang.authlib.UserAuthentication").getProtectionDomain().getCodeSource().getLocation();
-      FabricLauncherBase.getLauncher().propose(target);
-    } catch (final ClassNotFoundException e) {
+      AdventurePrelaunch.hackilyLoadForMixin("com.mojang.authlib.UserAuthentication");
+    } catch (final ClassNotFoundException | InvocationTargetException | IllegalAccessException e) {
       throw new RuntimeException("please fix fabric loader to enable transforming libraries normally", e);
     }
   }
+
+  /**
+   * Hackily load the package which a mixin may exist within.
+   *
+   * <p>YOU SHOULD NOT TARGET A CLASS WHICH YOU MIXIN TO. (this could be done to better avoid class loads)</p>
+   *
+   * @param pathOfAClass The path of any class within the package.
+   * @throws ClassNotFoundException if an unknown class name is used
+   * @throws InvocationTargetException if an error occurs while injecting
+   * @throws IllegalAccessException if an error occurs while injecting
+   */
+  static void hackilyLoadForMixin(final String pathOfAClass) throws ClassNotFoundException, InvocationTargetException, IllegalAccessException {
+    final URL url = Class.forName(pathOfAClass).getProtectionDomain().getCodeSource().getLocation();
+    ADD_URL_METHOD.invoke(KNOT_CLASSLOADER, url);
+  }
 }