Move common HitSampleInfo lookup to static method

osu.Game/Audio/HitSampleInfo.cs

@@ -17,6 +17,11 @@ public class HitSampleInfo : ISampleInfo
         public const string HIT_NORMAL = @"hitnormal";
         public const string HIT_CLAP = @"hitclap";
 
+        /// <summary>
+        /// All valid sample addition constants.
+        /// </summary>
+        public static IEnumerable<string> AllAdditions => new[] { HIT_WHISTLE, HIT_CLAP, HIT_FINISH };
+
         /// <summary>
         /// The bank to load the sample from.
         /// </summary>

osu.Game/Screens/Edit/Compose/Components/SelectionHandler.cs

@@ -331,10 +331,7 @@ public void RemoveHitSample(string sampleName)
         /// </summary>
         private void createStateBindables()
         {
-            // hit samples
-            var sampleTypes = new[] { HitSampleInfo.HIT_WHISTLE, HitSampleInfo.HIT_CLAP, HitSampleInfo.HIT_FINISH };
-
-            foreach (var sampleName in sampleTypes)
+            foreach (var sampleName in HitSampleInfo.AllAdditions)
             {
                 var bindable = new Bindable<TernaryState>
                 {