SPIGOT-2127: Add DamageCause.ENTITY_SWEEP_ATTACK

nms-patches/DamageSource.patch

@@ -0,0 +1,21 @@
+--- a/net/minecraft/server/DamageSource.java
++++ b/net/minecraft/server/DamageSource.java
+@@ -34,6 +34,18 @@
+     private boolean C;
+     private boolean D;
+     public String translationIndex;
++    // CraftBukkit start
++    private boolean sweep;
++
++    public boolean isSweep() {
++        return sweep;
++    }
++
++    public DamageSource sweep() {
++        this.sweep = true;
++        return this;
++    }
++    // CraftBukkit end
+ 
+     public static DamageSource mobAttack(EntityLiving entityliving) {
+         return new EntityDamageSource("mob", entityliving);

nms-patches/EntityHuman.patch

@@ -279,7 +279,7 @@
  
                                  if (entityliving != this && entityliving != entity && !this.r(entityliving) && this.h(entityliving) < 9.0D) {
 +                                    // CraftBukkit start - Only apply knockback if the damage hits
-+                                    if (entityliving.damageEntity(DamageSource.playerAttack(this), f4)) {
++                                    if (entityliving.damageEntity(DamageSource.playerAttack(this).sweep(), f4)) {
                                      entityliving.a(this, 0.4F, (double) MathHelper.sin(this.yaw * 0.017453292F), (double) (-MathHelper.cos(this.yaw * 0.017453292F)));
 -                                    entityliving.damageEntity(DamageSource.playerAttack(this), f4);
 +                                    }

src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java

@@ -464,7 +464,7 @@ public class CraftEventFactory {
             return event;
         } else if (source instanceof EntityDamageSource) {
             Entity damager = source.getEntity();
-            DamageCause cause = DamageCause.ENTITY_ATTACK;
+            DamageCause cause = (source.isSweep()) ? DamageCause.ENTITY_SWEEP_ATTACK : DamageCause.ENTITY_ATTACK;
 
             if (source instanceof EntityDamageSourceIndirect) {
                 damager = ((EntityDamageSourceIndirect) source).getProximateDamageSource();