Add method to get PluginClassLoader's classes map

BukkitUtils/src/main/java/eu/mikroskeem/utils/bukkit/ServerUtils.java

@@ -4,6 +4,7 @@ import eu.mikroskeem.utils.reflect.Reflect;
 import org.bukkit.Bukkit;
 import org.bukkit.plugin.java.JavaPlugin;
 import org.bukkit.plugin.java.JavaPluginLoader;
+import org.jetbrains.annotations.Nullable;
 
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
@@ -43,6 +44,7 @@ public class ServerUtils {
      * @return Plugin ClassLoader
      */
     @SuppressWarnings("unchecked")
+    @Nullable
     public static ClassLoader getPluginClassLoader(JavaPlugin plugin){
         /*
          * Note: CB/Spigot has PluginClassLoader package-private, PaperSpigot has public
@@ -83,6 +85,34 @@ public class ServerUtils {
         return null;
     }
 
+    /**
+     * Get PluginClassLoader classes map
+     * @param classLoader PluginClassLoader instance
+     * @return Classes map
+     * @throws RuntimeException if ClassLoader doesn't extend PluginClassLoader
+     */
+    @SuppressWarnings("unchecked")
+    @Nullable
+    public static Map<String, Class<?>> getClassesMap(ClassLoader classLoader){
+        Class<?> clClass = classLoader.getClass();
+        try {
+            Class<?> pluginClassLoader = checkNotNull(Reflect.getClass(
+                    "org.bukkit.plugin.java.PluginClassLoader"));
+            if(pluginClassLoader.isAssignableFrom(clClass)){
+                Field classesField = checkNotNull(Reflect.getField(clClass, "classes"));
+                return (Map<String, Class<?>>) checkNotNull(Reflect.readField(classesField, classLoader));
+            } else {
+                throw new RuntimeException(
+                        clClass.getName()
+                        + " does not extend "
+                        + pluginClassLoader.getName());
+            }
+        } catch(NullPointerException e){
+            e.printStackTrace();
+        }
+        return null;
+    }
+
     /**
      * Get NMS version of current running server
      * @return NMS version or 0 length string