DB/Creature: The instance_encounters extra flag (CREATURE_FLAG_EXTRA_DUNGEON_BOSS) now properly propagates to all difficulty entries (not just difficulty 0).

Port From (https://github.com/TrinityCore/TrinityCore/commit/6455f1c256e566da43d55583bca9c94c0d3139ce)

Source/Game/Entities/Creature/Creature.cs

@@ -2585,12 +2585,6 @@ namespace Game.Entities
                 GetVehicleKit().RelocatePassengers();
         }
 
-        public bool IsDungeonBoss()
-        {
-            CreatureTemplate cinfo = Global.ObjectMgr.GetCreatureTemplate(GetEntry());
-            return cinfo != null && (cinfo.FlagsExtra.HasAnyFlag(CreatureFlagsExtra.DungeonBoss));
-        }
-
         public float GetAggroRange(Unit target)
         {
             // Determines the aggro range for creatures (usually pets), used mainly for aggressive pet target selection.
@@ -2879,6 +2873,7 @@ namespace Game.Entities
         {
             return GetCreatureTemplate().InhabitType.HasAnyFlag(InhabitType.Air);
         }
+        public bool IsDungeonBoss() { return (GetCreatureTemplate().FlagsExtra.HasAnyFlag(CreatureFlagsExtra.DungeonBoss); }
 
         public void SetReactState(ReactStates st)
         {

Source/Game/Globals/ObjectManager.cs

@@ -5167,7 +5167,17 @@ namespace Game
                                 continue;
                             }
                             creatureInfo.FlagsExtra |= CreatureFlagsExtra.DungeonBoss;
-                            break;
+                            for (byte diff = 0; diff < SharedConst.MaxCreatureDifficulties; ++diff)
+                            {
+                                uint diffEntry = creatureInfo.DifficultyEntry[diff];
+                                if (diffEntry != 0)
+                                {
+                                    CreatureTemplate diffInfo = GetCreatureTemplate(diffEntry);
+                                    if (diffInfo != null)
+                                        diffInfo.FlagsExtra |= CreatureFlagsExtra.DungeonBoss;
+                                }
+                        }
+                        break;
                         }
                     case EncounterCreditType.CastSpell:
                         if (!Global.SpellMgr.HasSpellInfo(creditEntry))