Change classes that use FieldLoader to use read-only collections.

OpenRA.Mods.Common/Traits/Production.cs

@@ -11,6 +11,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using OpenRA.Primitives;
 using OpenRA.Traits;
 
@@ -21,7 +22,7 @@ namespace OpenRA.Mods.Common.Traits
 	{
 		[FieldLoader.Require]
 		[Desc("e.g. Infantry, Vehicles, Aircraft, Buildings")]
-		public readonly string[] Produces = [];
+		public readonly ImmutableArray<string> Produces = [];
 
 		[Desc("When owner is changed, should the Faction be updated to the new owner's faction?")]
 		public readonly bool UpdateFactionOnOwnerChange = false;