SPIGOT-2540: Add nullability annotations to entire Bukkit API

By: Darkyenus <darkyenus@gmail.com>

paper-api/src/main/java/org/bukkit/material/Attachable.java

@@ -1,6 +1,7 @@
 package org.bukkit.material;
 
 import org.bukkit.block.BlockFace;
+import org.jetbrains.annotations.NotNull;
 
 /**
  * Indicates that a block can be attached to another block
@@ -12,5 +13,6 @@ public interface Attachable extends Directional {
      *
      * @return BlockFace attached to
      */
+    @NotNull
     public BlockFace getAttachedFace();
 }

paper-api/src/main/java/org/bukkit/material/Colorable.java

@@ -1,6 +1,8 @@
 package org.bukkit.material;
 
 import org.bukkit.DyeColor;
+import org.bukkit.UndefinedNullability;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * An object that can be colored.
@@ -15,6 +17,7 @@ public interface Colorable {
      *
      * @return The DyeColor of this object.
      */
+    @Nullable
     public DyeColor getColor();
 
     /**
@@ -24,7 +27,8 @@ public interface Colorable {
      * object has a special default color (e.g Shulkers).
      *
      * @param color The color of the object, as a DyeColor.
+     * @throws NullPointerException if argument is null and this implementation does not support null
      */
-    public void setColor(DyeColor color);
+    public void setColor(@UndefinedNullability("defined by subclass") DyeColor color);
 
 }

paper-api/src/main/java/org/bukkit/material/Directional.java

@@ -1,6 +1,7 @@
 package org.bukkit.material;
 
 import org.bukkit.block.BlockFace;
+import org.jetbrains.annotations.NotNull;
 
 public interface Directional {
 
@@ -9,12 +10,13 @@ public interface Directional {
      *
      * @param face The facing direction
      */
-    public void setFacingDirection(BlockFace face);
+    public void setFacingDirection(@NotNull BlockFace face);
 
     /**
      * Gets the direction this block is facing
      *
      * @return the direction this block is facing
      */
+    @NotNull
     public BlockFace getFacing();
 }

paper-api/src/main/java/org/bukkit/material/types/MushroomBlockTexture.java

@@ -5,6 +5,8 @@ import java.util.Map;
 import org.bukkit.block.BlockFace;
 
 import com.google.common.collect.Maps;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Represents the different textured blocks of mushroom.
@@ -70,7 +72,7 @@ public enum MushroomBlockTexture {
     private final Byte data;
     private final BlockFace capFace;
 
-    private MushroomBlockTexture(final int data, final BlockFace capFace) {
+    private MushroomBlockTexture(final int data, @Nullable final BlockFace capFace) {
         this.data = (byte) data;
         this.capFace = capFace;
     }
@@ -91,6 +93,7 @@ public enum MushroomBlockTexture {
      *
      * @return The cap face
      */
+    @Nullable
     public BlockFace getCapFace() {
         return capFace;
     }
@@ -104,6 +107,7 @@ public enum MushroomBlockTexture {
      * @deprecated Magic value
      */
     @Deprecated
+    @Nullable
     public static MushroomBlockTexture getByData(final byte data) {
         return BY_DATA.get(data);
     }
@@ -117,7 +121,8 @@ public enum MushroomBlockTexture {
      *
      * @see BlockFace
      */
-    public static MushroomBlockTexture getCapByFace(final BlockFace face) {
+    @Nullable
+    public static MushroomBlockTexture getCapByFace(@Nullable final BlockFace face) {
         return BY_BLOCKFACE.get(face);
     }