[ci-skip] Mention missing World#regenerateChunk implementation in jd (#12109)

* Mention missing impl

* Clean the implementation out of years old code

* Change the jd comment

* Move to default method

---------

Co-authored-by: Bjarne Koll <lynxplay101@gmail.com>

paper-server/src/main/java/org/bukkit/craftbukkit/CraftWorld.java

@@ -470,33 +470,6 @@ public class CraftWorld extends CraftRegionAccessor implements World {
         return !this.isChunkLoaded(x, z);
     }
 
-    @Override
-    public boolean regenerateChunk(int x, int z) {
-        org.spigotmc.AsyncCatcher.catchOp("chunk regenerate"); // Spigot
-        throw new UnsupportedOperationException("Not supported in this Minecraft version! Unless you can fix it, this is not a bug :)");
-        /*
-        if (!unloadChunk0(x, z, false)) {
-            return false;
-        }
-        warnUnsafeChunk("regenerating a faraway chunk", x, z); // Paper
-
-        final long chunkKey = ChunkCoordIntPair.pair(x, z);
-        world.getChunkProvider().unloadQueue.remove(chunkKey);
-
-        net.minecraft.server.Chunk chunk = world.getChunkProvider().generateChunk(x, z);
-        PlayerChunk playerChunk = world.getPlayerChunkMap().getChunk(x, z);
-        if (playerChunk != null) {
-            playerChunk.chunk = chunk;
-        }
-
-        if (chunk != null) {
-            refreshChunk(x, z);
-        }
-
-        return chunk != null;
-        */
-    }
-
     @Override
     public boolean refreshChunk(int x, int z) {
         ChunkHolder playerChunk = this.world.getChunkSource().chunkMap.getVisibleChunkIfPresent(ChunkPos.asLong(x, z));