Start of update() + added sign

src/main/java/org/bukkit/craftbukkit/block/CraftBlockState.java

@@ -143,4 +143,20 @@ public class CraftBlockState implements BlockState {
     public Block getBlock() {
         return world.getBlockAt(x, y, z);
     }
+
+    public boolean update() {
+        return update(false);
+    }
+
+    public boolean update(boolean force) { // TODO
+        Block block = getBlock();
+
+        synchronized (block) {
+            if (block.getType() != this.getType()) {
+                return false;
+            }
+        }
+
+        return true;
+    }
 }

src/main/java/org/bukkit/craftbukkit/block/CraftSign.java

@@ -0,0 +1,27 @@
+
+package org.bukkit.craftbukkit.block;
+
+import org.bukkit.Block;
+import org.bukkit.Chunk;
+import org.bukkit.Material;
+import org.bukkit.World;
+import org.bukkit.block.Sign;
+import org.bukkit.craftbukkit.CraftWorld;
+
+public class CraftSign extends CraftBlockState implements Sign {
+    public CraftSign(final CraftWorld world, final int x, final int y, final int z, final int type, final byte data) {
+        super(world, x, y, z, type, data);
+    }
+
+    public String[] getLines() {
+        throw new UnsupportedOperationException("Not supported yet.");
+    }
+
+    public String getLine(int index) throws IndexOutOfBoundsException {
+        throw new UnsupportedOperationException("Not supported yet.");
+    }
+
+    public void setLine(int index, String line) throws IndexOutOfBoundsException {
+        throw new UnsupportedOperationException("Not supported yet.");
+    }
+}