add API for GT Modules to subscribe to the Ore and Terrain Gen buses

src/main/java/gregtech/api/modules/IGregTechModule.java

@@ -55,11 +55,35 @@ default void serverStopped(FMLServerStoppedEvent event) {}
     default void registerPackets() {}
 
     /**
-     * @return A list of classes to subscribe to the Forge event bus.
-     *         As the class gets subscribed, not any specific instance, event handlers must be static!
+     * The class itself gets subscribed, instead of a class instance, so event handlers <strong>must</strong> be
+     * {@code static}.
+     *
+     * @return A list of classes to subscribe to the Forge Event Bus,
+     *         {@link net.minecraftforge.common.MinecraftForge#EVENT_BUS}.
      */
-    @NotNull
-    default List<Class<?>> getEventBusSubscribers() {
+    default @NotNull List<Class<?>> getEventBusSubscribers() {
+        return Collections.emptyList();
+    }
+
+    /**
+     * The class itself gets subscribed, instead of a class instance, so event handlers <strong>must</strong> be
+     * {@code static}.
+     *
+     * @return A list of classes to subscribe to the Forge Terrain Gen Bus,
+     *         {@link net.minecraftforge.common.MinecraftForge#TERRAIN_GEN_BUS}.
+     */
+    default @NotNull List<Class<?>> getTerrainGenBusSubscribers() {
+        return Collections.emptyList();
+    }
+
+    /**
+     * The class itself gets subscribed, instead of a class instance, so event handlers <strong>must</strong> be
+     * {@code static}.
+     *
+     * @return A list of classes to subscribe to the Forge Ore Gen Bus,
+     *         {@link net.minecraftforge.common.MinecraftForge#ORE_GEN_BUS}.
+     */
+    default @NotNull List<Class<?>> getOreGenBusSubscribers() {
         return Collections.emptyList();
     }
 

src/main/java/gregtech/modules/ModuleManager.java

@@ -101,6 +101,12 @@ public void setup(ASMDataTable asmDataTable, File configDirectory) {
             for (Class<?> clazz : module.getEventBusSubscribers()) {
                 MinecraftForge.EVENT_BUS.register(clazz);
             }
+            for (Class<?> clazz : module.getTerrainGenBusSubscribers()) {
+                MinecraftForge.TERRAIN_GEN_BUS.register(clazz);
+            }
+            for (Class<?> clazz : module.getOreGenBusSubscribers()) {
+                MinecraftForge.ORE_GEN_BUS.register(clazz);
+            }
         }
     }