Simplify code of the ExecutableProvider class

Author: AlexUstinov

Orm/Xtensive.Orm/Orm/Rse/Providers/ExecutableProvider.cs

@@ -1,4 +1,4 @@
-// Copyright (C) 2008-2020 Xtensive LLC.
+// Copyright (C) 2008-2022 Xtensive LLC.
 // This code is distributed under MIT license terms.
 // See the License.txt file in the project root for more information.
 // Created by: Alexey Kochetov
@@ -23,7 +23,7 @@ public abstract class ExecutableProvider : Provider
     /// <summary>
     /// Gets the provider this provider is compiled from.
     /// </summary>
-    public CompilableProvider Origin { get; private set; }
+    public CompilableProvider Origin { get; }
 
 
     #region OnXxxEnumerate methods (to override)

Orm/Xtensive.Orm/Orm/Rse/Providers/ExecutableProvider{TOrigin}.cs

@@ -1,6 +1,6 @@
-// Copyright (C) 2003-2010 Xtensive LLC.
-// All rights reserved.
-// For conditions of distribution and use, see license.
+// Copyright (C) 2008-2022 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
 // Created by: Alex Yakunin
 // Created:    2008.08.13
 
@@ -20,10 +20,7 @@ public abstract class ExecutableProvider<TOrigin> : ExecutableProvider
     /// <summary>
     /// Gets the provider this provider is compiled from.
     /// </summary>
-    public new TOrigin Origin {
-      get { return (TOrigin) base.Origin; }
-    }
-
+    public new TOrigin Origin => (TOrigin) base.Origin;
 
     // Constructors