Rollback QueryEventArgs to class

Author: SergeiPavlov

Orm/Xtensive.Orm/Orm/QueryEventArgs.cs

@@ -11,12 +11,12 @@ namespace Xtensive.Orm
   /// Event args for <see cref="SessionEventAccessor.QueryExecuting"/>
   /// and <see cref="SessionEventAccessor.QueryExecuted"/>.
   /// </summary>
-  public readonly struct QueryEventArgs
+  public class QueryEventArgs : EventArgs
   {
     /// <summary>
     /// Gets executed expression.
     /// </summary>
-    public Expression Expression { get; }
+    public Expression Expression { get; set; }
 
     /// <summary>
     /// Gets exception, thrown during expression execution. <see langword="null" /> if expression executed successfully.

Orm/Xtensive.Orm/Orm/SessionEventAccessor.cs

@@ -1,4 +1,4 @@
-// Copyright (C) 2010-2020 Xtensive LLC.
+// Copyright (C) 2010-2022 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
@@ -256,22 +256,18 @@ internal void NotifyDbCommandExecuted(DbCommand command, Exception exception = n
     internal Expression NotifyQueryExecuting(Expression expression)
     {
       var args = new QueryEventArgs(expression);
-      if (QueryExecuting!=null) {
-        QueryExecuting(this, args);
-      }
+      QueryExecuting?.Invoke(this, args);
       return args.Expression;
     }
 
     internal void NotifyQueryExecuted(Expression expression, Exception exception = null)
     {
-      if (QueryExecuted!=null)
-        QueryExecuted(this, new QueryEventArgs(expression, exception));
+      QueryExecuted?.Invoke(this, new QueryEventArgs(expression, exception));
     }
 
     internal void NotifyDisposing()
     {
-      if (Disposing!=null)
-        Disposing(this, EventArgs.Empty);
+      Disposing?.Invoke(this, EventArgs.Empty);
     }
 
     internal void NotifyPersisting()
@@ -509,4 +505,4 @@ internal SessionEventAccessor(Session session, bool systemEvents)
       SystemEvents = systemEvents;
     }
   }
-}
+}