Get rid of SingletonEnumerable

Author: bahusoid

src/NHibernate.Test/UtilityTest/SingletonEnumerableFixture.cs

@@ -1,9 +1,11 @@
+using System;
 using System.Collections;
 using NHibernate.Util;
 using NUnit.Framework;
 
 namespace NHibernate.Test.UtilityTest
 {
+	[Obsolete]
 	[TestFixture]
 	public class SingletonEnumerableFixture
 	{
@@ -46,4 +48,4 @@ public void ShouldWorkAsEnumerator()
 			Assert.That(i, Is.EqualTo(1));
 		}
 	}
-}
+}

src/NHibernate/Mapping/RootClass.cs

@@ -89,12 +89,12 @@ public override IEnumerable<Property> PropertyClosureIterator
 		/// </remarks>
 		public override IEnumerable<Table> TableClosureIterator
 		{
-			get { return new SingletonEnumerable<Table>(Table); }
+			get { return new[] {Table}; }
 		}
 
 		public override IEnumerable<IKeyValue> KeyClosureIterator
 		{
-			get { return new SingletonEnumerable<IKeyValue>(Key); }
+			get { return new[] {Key}; }
 		}
 
 		/// <summary>

src/NHibernate/Util/SingletonEnumerable.cs

@@ -1,8 +1,11 @@
+using System;
 using System.Collections;
 using System.Collections.Generic;
 
 namespace NHibernate.Util
 {
+	//Since 5.2
+	[Obsolete("This class has no more usages and will be removed in a future version")]
 	public sealed class SingletonEnumerable<T> : IEnumerable<T>
 	{
 		private readonly T value;
@@ -78,4 +81,4 @@ object IEnumerator.Current
 			#endregion
 		}
 	}
-}
+}