Use a new instantiator instead of changing the old one

And obsolete the old one

To be squashed.

Author: fredericDelaporte

src/NHibernate/Tuple/DynamicEntityInstantiator.cs

@@ -0,0 +1,64 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using NHibernate.Mapping;
+
+namespace NHibernate.Tuple
+{
+	[Serializable]
+	public class DynamicEntityInstantiator : IInstantiator
+	{
+		public const string Key = "$type$";
+
+		private readonly string _entityName;
+		private readonly HashSet<string> _isInstanceEntityNames = new HashSet<string>();
+
+		public DynamicEntityInstantiator(PersistentClass mappingInfo)
+		{
+			_entityName = mappingInfo.EntityName;
+			_isInstanceEntityNames.Add(_entityName);
+			if (mappingInfo.HasSubclasses)
+			{
+				foreach (var subclassInfo in mappingInfo.SubclassClosureIterator)
+					_isInstanceEntityNames.Add(subclassInfo.EntityName);
+			}
+		}
+
+		protected virtual IDictionary<string, object> GenerateMap()
+		{
+			return new Dictionary<string, object>();
+		}
+
+		#region IInstantiator Members
+
+		public object Instantiate(object id)
+		{
+			return Instantiate();
+		}
+
+		public object Instantiate()
+		{
+			var map = GenerateMap();
+			if (_entityName != null)
+			{
+				map[Key] = _entityName;
+			}
+
+			return map;
+		}
+
+		public bool IsInstance(object obj)
+		{
+			if (!(obj is IDictionary<string, object> that))
+				return false;
+			if (_entityName == null)
+				return true;
+
+			var type = (string) that[Key];
+			return type == null || _isInstanceEntityNames.Contains(type);
+
+		}
+
+		#endregion
+	}
+}

src/NHibernate/Tuple/DynamicMapInstantiator.cs

@@ -5,6 +5,8 @@
 
 namespace NHibernate.Tuple
 {
+	//Since v5.2
+	[Obsolete("This class is not used and will be removed in a future version.")]
 	[Serializable]
 	public class DynamicMapInstantiator : IInstantiator
 	{
@@ -13,8 +15,6 @@ public class DynamicMapInstantiator : IInstantiator
 		private readonly string entityName;
 		private readonly HashSet<string> isInstanceEntityNames = new HashSet<string>();
 
-		//Since v5.2
-		[Obsolete("This constructor is not used and will be removed in a future version.")]
 		public DynamicMapInstantiator()
 		{
 			entityName = null;
@@ -50,7 +50,7 @@ public object Instantiate()
 
 		protected virtual IDictionary GenerateMap()
 		{
-			return new Dictionary<string, object>();
+			return new Hashtable();
 		}
 
 		public bool IsInstance(object obj)

src/NHibernate/Tuple/Entity/DynamicMapEntityTuplizer.cs

@@ -57,7 +57,7 @@ protected override ISetter BuildPropertySetter(Mapping.Property mappedProperty,
 
 		protected override IInstantiator BuildInstantiator(PersistentClass mappingInfo)
 		{
-			return new DynamicMapInstantiator(mappingInfo);
+			return new DynamicEntityInstantiator(mappingInfo);
 		}
 
 		protected override IProxyFactory BuildProxyFactory(PersistentClass mappingInfo, IGetter idGetter,