Fix #750 - AliasToBean failure with criteria grouping

Author: fredericDelaporte

src/NHibernate/Transform/AliasToBeanResultTransformer.cs

@@ -121,6 +121,10 @@ public override IList TransformList(IList collection)
 		/// same visibility and inheritance depth.</exception>
 		private void SetProperty(string alias, object value, object resultObj)
 		{
+			if (alias == null)
+				// Grouping properties in criteria are selected without alias, just ignore them.
+				return;
+
 			if (TrySet(alias, value, resultObj, _propertiesByNameCaseSensitive))
 				return;
 			if (TrySet(alias, value, resultObj, _fieldsByNameCaseSensitive))
@@ -299,4 +303,4 @@ public override int GetHashCode()
 
 		#endregion
 	}
-}
+}