Allow for optional localised text notifications.

OpenRA.Game/Translation.cs

@@ -27,6 +27,7 @@ namespace OpenRA
 	[AttributeUsage(AttributeTargets.Field)]
 	public sealed class TranslationReferenceAttribute : Attribute
 	{
+		public readonly bool Optional;
 		public readonly string[] RequiredVariableNames;
 		public readonly LintDictionaryReference DictionaryReference;
 
@@ -41,6 +42,11 @@ namespace OpenRA
 		{
 			DictionaryReference = dictionaryReference;
 		}
+
+		public TranslationReferenceAttribute(bool optional)
+		{
+			Optional = optional;
+		}
 	}
 
 	public class Translation

OpenRA.Mods.Common/Lint/CheckTranslationReference.cs

@@ -46,7 +46,9 @@ namespace OpenRA.Mods.Common.Lint
 						{
 							if (key == null)
 							{
+								if (!translationReference.Optional)
 									emitError($"Trait `{traitInfo.InstanceName}` on field `{field.Name}` has an empty translation reference.");
+
 								continue;
 							}