Annotate animation in ClientboundAnimatePacket as Nullable (#743)

Author: Konicai

src/main/java/com/github/steveice10/mc/protocol/data/game/entity/player/Animation.java

@@ -2,6 +2,7 @@
 
 import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
 import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
+import org.jetbrains.annotations.Nullable;
 
 public enum Animation {
     SWING_ARM(0),
@@ -20,8 +21,9 @@ public int getId() {
         return id;
     }
 
-    private static Int2ObjectMap<Animation> VALUES = new Int2ObjectOpenHashMap<>();
+    private static final Int2ObjectMap<Animation> VALUES = new Int2ObjectOpenHashMap<>();
 
+    @Nullable
     public static Animation from(int id) {
         return VALUES.get(id);
     }

src/main/java/com/github/steveice10/mc/protocol/packet/ingame/clientbound/entity/ClientboundAnimatePacket.java

@@ -6,8 +6,8 @@
 import io.netty.buffer.ByteBuf;
 import lombok.AllArgsConstructor;
 import lombok.Data;
-import lombok.NonNull;
 import lombok.With;
+import org.jetbrains.annotations.Nullable;
 
 import java.io.IOException;
 
@@ -16,7 +16,7 @@
 @AllArgsConstructor
 public class ClientboundAnimatePacket implements MinecraftPacket {
     private final int entityId;
-    private final @NonNull Animation animation;
+    private final @Nullable Animation animation;
 
     public ClientboundAnimatePacket(ByteBuf in, MinecraftCodecHelper helper) throws IOException {
         this.entityId = helper.readVarInt(in);
@@ -26,6 +26,10 @@ public ClientboundAnimatePacket(ByteBuf in, MinecraftCodecHelper helper) throws
     @Override
     public void serialize(ByteBuf out, MinecraftCodecHelper helper) throws IOException {
         helper.writeVarInt(out, this.entityId);
-        out.writeByte(this.animation.getId());
+        if (this.animation == null) {
+            out.writeByte(-1); // Client does nothing on unknown ID
+        } else {
+            out.writeByte(this.animation.getId());
+        }
     }
 }