SPIGOT-2953: Set damager for fireworks

nms-patches/EntityFireworks.patch

@@ -1,6 +1,14 @@
 --- a/net/minecraft/server/EntityFireworks.java
 +++ b/net/minecraft/server/EntityFireworks.java
-@@ -117,8 +117,12 @@
+@@ -2,6 +2,7 @@
+ 
+ import java.util.Iterator;
+ import java.util.List;
++import org.bukkit.craftbukkit.event.CraftEventFactory; // CraftBukkit
+ 
+ public class EntityFireworks extends Entity {
+ 
+@@ -117,8 +118,12 @@
          }
  
          if (!this.world.isClientSide && this.ticksFlown > this.expectedLifespan) {
@@ -15,3 +23,13 @@
              this.die();
          }
  
+@@ -136,7 +141,9 @@
+ 
+         if (f > 0.0F) {
+             if (this.e != null) {
++                CraftEventFactory.entityDamage = this; // CraftBukkit
+                 this.e.damageEntity(DamageSource.t, (float) (5 + nbttaglist.size() * 2));
++                CraftEventFactory.entityDamage = null; // CraftBukkit
+             }
+ 
+             double d0 = 5.0D;