Fix scaling for player health. Fixes BUKKIT-4431

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

@@ -233,8 +233,8 @@ public class EntityPlayer extends EntityHuman implements ICrafting {
             }
 
             if (this.getHealth() != this.bP || this.bQ != this.foodData.a() || this.foodData.e() == 0.0F != this.bR) {
-                // CraftBukkit - this.getHealth() -> this.getScaledHealth() - Magic number 20 -> original max health
+                // CraftBukkit - Optionally scale health
-                this.playerConnection.sendPacket(new Packet8UpdateHealth((float) (this.getHealth() * this.getMaxHealth() / 20.0D), this.foodData.a(), this.foodData.e()));
+                this.playerConnection.sendPacket(new Packet8UpdateHealth(getBukkitEntity().getScaledHealth(), this.foodData.a(), this.foodData.e()));
                 this.bP = this.getHealth();
                 this.bQ = this.foodData.a();
                 this.bR = this.foodData.e() == 0.0F;

src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java

@@ -61,6 +61,7 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
     private final Set<String> channels = new HashSet<String>();
     private final Map<String, Player> hiddenPlayers = new MapMaker().softValues().makeMap();
     private int hash = 0;
+    private boolean scaledHealth;
 
     public CraftPlayer(CraftServer server, EntityPlayer entity) {
         super(server, entity);
@@ -997,4 +998,16 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
 
         this.server.getScoreboardManager().setPlayerBoard(this, scoreboard);
     }
+
+    public float getScaledHealth() {
+        return (float) (this.scaledHealth ? getHealth() / getMaxHealth() * 20.0D : getHealth());
+    }
+
+    public void setScaleHealth(boolean scale) {
+        this.scaledHealth = scale;
+    }
+
+    public boolean isScaledHealth() {
+        return this.scaledHealth;
+    }
 }