Added for diff visibility:

- ChunkProviderGenerate
- ChunkProviderFlat
- ChunkProviderHell
- ChunkProviderTheEnd

src/main/java/net/minecraft/server/ChunkProviderFlat.java

@@ -0,0 +1,95 @@
+package net.minecraft.server;
+
+import java.util.List;
+import java.util.Random;
+
+public class ChunkProviderFlat implements IChunkProvider {
+
+    private World a;
+    private Random b;
+    private final boolean c;
+    private WorldGenVillage d = new WorldGenVillage(1);
+
+    public ChunkProviderFlat(World world, long i, boolean flag) {
+        this.a = world;
+        this.c = flag;
+        this.b = new Random(i);
+    }
+
+    private void a(byte[] abyte) {
+        int i = abyte.length / 256;
+
+        for (int j = 0; j < 16; ++j) {
+            for (int k = 0; k < 16; ++k) {
+                for (int l = 0; l < i; ++l) {
+                    int i1 = 0;
+
+                    if (l == 0) {
+                        i1 = Block.BEDROCK.id;
+                    } else if (l <= 2) {
+                        i1 = Block.DIRT.id;
+                    } else if (l == 3) {
+                        i1 = Block.GRASS.id;
+                    }
+
+                    abyte[j << 11 | k << 7 | l] = (byte) i1;
+                }
+            }
+        }
+    }
+
+    public Chunk getChunkAt(int i, int j) {
+        return this.getOrCreateChunk(i, j);
+    }
+
+    public Chunk getOrCreateChunk(int i, int j) {
+        byte[] abyte = new byte['\u8000'];
+
+        this.a(abyte);
+        Chunk chunk = new Chunk(this.a, abyte, i, j);
+
+        if (this.c) {
+            this.d.a(this, this.a, i, j, abyte);
+        }
+
+        chunk.initLighting();
+        return chunk;
+    }
+
+    public boolean isChunkLoaded(int i, int j) {
+        return true;
+    }
+
+    public void getChunkAt(IChunkProvider ichunkprovider, int i, int j) {
+        this.b.setSeed(this.a.getSeed());
+        long k = this.b.nextLong() / 2L * 2L + 1L;
+        long l = this.b.nextLong() / 2L * 2L + 1L;
+
+        this.b.setSeed((long) i * k + (long) j * l ^ this.a.getSeed());
+        if (this.c) {
+            this.d.a(this.a, this.b, i, j);
+        }
+    }
+
+    public boolean saveChunks(boolean flag, IProgressUpdate iprogressupdate) {
+        return true;
+    }
+
+    public boolean unloadChunks() {
+        return false;
+    }
+
+    public boolean canSave() {
+        return true;
+    }
+
+    public List getMobsFor(EnumCreatureType enumcreaturetype, int i, int j, int k) {
+        BiomeBase biomebase = this.a.getBiome(i, k);
+
+        return biomebase == null ? null : biomebase.getMobs(enumcreaturetype);
+    }
+
+    public ChunkPosition findNearestMapFeature(World world, String s, int i, int j, int k) {
+        return null;
+    }
+}