Fix CA1825 warnings on empty array initialisation.

OpenRA.Mods.Common/Traits/SupportPowers/NukePower.cs

@@ -9,6 +9,7 @@
  */
 #endregion
 
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using OpenRA.GameRules;
@@ -61,7 +62,7 @@ namespace OpenRA.Mods.Common.Traits
 
 		[SequenceReference(nameof(TrailImage), allowNullImage: true)]
 		[Desc("Loop a randomly chosen sequence of TrailImage from this list while this projectile is moving.")]
-		public readonly string[] TrailSequences = { };
+		public readonly string[] TrailSequences = Array.Empty<string>();
 
 		[Desc("Interval in ticks between each spawned Trail animation.")]
 		public readonly int TrailInterval = 1;