Introduced AbstractMask as a superclass to all implementors of the Mask interface.

src/main/java/com/sk89q/worldedit/masks/AbstractMask.java

@@ -0,0 +1,11 @@
+package com.sk89q.worldedit.masks;
+
+import com.sk89q.worldedit.LocalPlayer;
+import com.sk89q.worldedit.LocalSession;
+import com.sk89q.worldedit.Vector;
+
+public abstract class AbstractMask implements Mask {
+    @Override
+    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
+    }
+}

src/main/java/com/sk89q/worldedit/masks/BiomeTypeMask.java

@@ -5,12 +5,10 @@ import java.util.Set;
 
 import com.sk89q.worldedit.BiomeType;
 import com.sk89q.worldedit.EditSession;
-import com.sk89q.worldedit.LocalPlayer;
-import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.Vector2D;
 
-public class BiomeTypeMask implements Mask {
+public class BiomeTypeMask extends AbstractMask {
     private final Set<BiomeType> biomes;
 
     public BiomeTypeMask() {
@@ -21,9 +19,6 @@ public class BiomeTypeMask implements Mask {
         this.biomes = biomes;
     }
 
-    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
-    }
-
     public boolean matches2D(EditSession editSession, Vector2D pos) {
         BiomeType biome = editSession.getWorld().getBiome(pos);
         return biomes.contains(biome);

src/main/java/com/sk89q/worldedit/masks/BlockMask.java

@@ -5,12 +5,10 @@ import java.util.HashSet;
 import java.util.Set;
 
 import com.sk89q.worldedit.EditSession;
-import com.sk89q.worldedit.LocalPlayer;
-import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.blocks.BaseBlock;
 
-public class BlockMask implements Mask {
+public class BlockMask extends AbstractMask {
     private final Set<BaseBlock> blocks;
 
     public BlockMask() {
@@ -34,9 +32,6 @@ public class BlockMask implements Mask {
         blocks.addAll(blocks);
     }
 
-    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
-    }
-
     @Override
     public boolean matches(EditSession editSession, Vector pos) {
         BaseBlock block = editSession.getBlock(pos);

src/main/java/com/sk89q/worldedit/masks/CombinedMask.java

@@ -26,7 +26,7 @@ import com.sk89q.worldedit.LocalPlayer;
 import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 
-public class CombinedMask implements Mask {
+public class CombinedMask extends AbstractMask {
     private final List<Mask> masks = new ArrayList<Mask>();
 
     public CombinedMask() {

src/main/java/com/sk89q/worldedit/masks/ExistingBlockMask.java

@@ -20,15 +20,10 @@
 package com.sk89q.worldedit.masks;
 
 import com.sk89q.worldedit.EditSession;
-import com.sk89q.worldedit.LocalPlayer;
-import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.blocks.BlockID;
 
-public class ExistingBlockMask implements Mask {
-    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
-    }
-
+public class ExistingBlockMask extends AbstractMask {
     @Override
     public boolean matches(EditSession editSession, Vector pos) {
         return editSession.getBlockType(pos) != BlockID.AIR;

src/main/java/com/sk89q/worldedit/masks/InvertedMask.java

@@ -5,7 +5,7 @@ import com.sk89q.worldedit.LocalPlayer;
 import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 
-public class InvertedMask implements Mask {
+public class InvertedMask extends AbstractMask {
     private final Mask mask;
 
     public InvertedMask(Mask mask) {

src/main/java/com/sk89q/worldedit/masks/Mask.java

@@ -26,7 +26,9 @@ import com.sk89q.worldedit.Vector;
 
 /**
  * Base matcher for the block filtering framework. Implementing classes
- * can be used to filter blocks to set or replace
+ * can be used to filter blocks to set or replace.
+ * <p>
+ * <u>Do NOT</u> implement this interface. Extend {@link AbstractMask} instead.
  *
  * @author sk89q
  */

src/main/java/com/sk89q/worldedit/masks/RandomMask.java

@@ -1,21 +1,15 @@
 package com.sk89q.worldedit.masks;
 
 import com.sk89q.worldedit.EditSession;
-import com.sk89q.worldedit.LocalPlayer;
-import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 
-public class RandomMask implements Mask {
+public class RandomMask extends AbstractMask {
     private final double ratio;
 
     public RandomMask(double ratio) {
         this.ratio = ratio;
     }
 
-    @Override
-    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
-    }
-
     @Override
     public boolean matches(EditSession editSession, Vector pos) {
         return Math.random() < ratio;

src/main/java/com/sk89q/worldedit/masks/RegionMask.java

@@ -20,21 +20,16 @@
 package com.sk89q.worldedit.masks;
 
 import com.sk89q.worldedit.EditSession;
-import com.sk89q.worldedit.LocalPlayer;
-import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.regions.Region;
 
-public class RegionMask implements Mask {
+public class RegionMask extends AbstractMask {
     private final Region region;
 
     public RegionMask(Region region) {
         this.region = region.clone();
     }
 
-    public void prepare(LocalSession session, LocalPlayer player, Vector target) {
-    }
-
     @Override
     public boolean matches(EditSession editSession, Vector pos) {
         return region.contains(pos);

src/main/java/com/sk89q/worldedit/masks/UnderOverlayMask.java

@@ -31,7 +31,7 @@ import com.sk89q.worldedit.blocks.BaseBlock;
  *
  * @author 1337
  */
-public class UnderOverlayMask implements Mask {
+public class UnderOverlayMask extends AbstractMask {
     private final int yMod;
     private Mask mask;