How to set up an ArcGIS Network Analyst extension solve to work with the undo/redo stack

public void SolveWithinUndoRedoOperation()
{
    // Get the extension and the NAWindow to have access to the undo/redo stack.
    ESRI.ArcGIS.Controls.IEngineNetworkAnalystEnvironment engineNAEnvironment = new
        ESRI.ArcGIS.Controls.EngineNetworkAnalystEnvironmentClass();
    ESRI.ArcGIS.Controls.IEngineNAWindow naWindow = engineNAEnvironment.NAWindow;

    // Get the context and solver on which you are doing analysis.
    ESRI.ArcGIS.NetworkAnalyst.INAContext naContext =
        naWindow.ActiveAnalysis.Context;
    ESRI.ArcGIS.NetworkAnalyst.INASolver naSolver = naContext.Solver;

    // Set up the track cancel to allow the user to stop the solve at any time.
    ESRI.ArcGIS.esriSystem.ITrackCancel trackCancel = new
        ESRI.ArcGIS.Display.CancelTrackerClass();
    trackCancel.CancelOnClick = false;
    trackCancel.CancelOnKeyPress = true;

    // Use StartOperation to start an edit operation on items in an NAClass. It should be followed with a call to StopOperation.  
    // The combination of these two calls adds an edit operation to ArcMap that can be undone/redone using the undo/redo buttons in ArcMap.
    naWindow.StartOperation(naContext);

    // Turning on DelayEvents stops the NAWindow from responding to system events, until it is turned back on.
    //  This will hold off on updating NALocationObjects in the window, helping the system be more responsive during solve.
    naWindow.DelayEvents(null, true);

    try
    {
        naSolver.Solve(naContext, new ESRI.ArcGIS.Geodatabase.GPMessagesClass(),
            trackCancel);
        naWindow.Message = "Solve completed";

        // Stop the operation. The message passed shows on the Undo button.
        naWindow.StopOperation(naContext, "Solve");
    }
    catch (System.Exception e)
    {
        // User aborted this by choice, roll it back.
        if (e.Message == "Solve operation cancelled by user." ||
            !trackCancel.Continue())
        {
            naWindow.Message = e.Message;

            // AbortOperation will stop and automatically undo the current operation.
            naWindow.AbortOperation(naContext);
        }
        else
        {
            naWindow.StopOperation(naContext, "Solve");
            naWindow.Message = "Error: " + e.Message;
        }
    }
    // Resume listening to events.
    naWindow.DelayEvents(null, false);

    // Notify clients that the context has changed.
    var naContextEdit = naContext as ESRI.ArcGIS.NetworkAnalyst.INAContextEdit;
    naContextEdit.ContextChanged();

    // Update the NAWindow to have the latest contents.
    naWindow.UpdateContent(null);
}

Public Sub SolveWithinUndoRedoOperation()
    ' Get the extension and the NAWindow to have access to the undo/redo stack.
    Dim engineNAEnvironment As ESRI.ArcGIS.Controls.IEngineNetworkAnalystEnvironment = New ESRI.ArcGIS.Controls.EngineNetworkAnalystEnvironmentClass()
    Dim naWindow As ESRI.ArcGIS.Controls.IEngineNAWindow = engineNAEnvironment.NAWindow
    
    ' Get the context and solver on which you are doing analysis.
    Dim naContext As ESRI.ArcGIS.NetworkAnalyst.INAContext = naWindow.ActiveAnalysis.Context
    Dim naSolver As ESRI.ArcGIS.NetworkAnalyst.INASolver = naContext.Solver
    
    ' Set up the track cancel to allow the user to stop the solve at any time.
    Dim trackCancel As ESRI.ArcGIS.esriSystem.ITrackCancel = New ESRI.ArcGIS.Display.CancelTrackerClass()
    trackCancel.CancelOnClick = False
    trackCancel.CancelOnKeyPress = True
    
    ' Use StartOperation to start an edit operation on items in an NAClass. It should be followed with a call to StopOperation.
    ' The combination of these two calls adds an edit operation to ArcMap that can be undone/redone using the undo/redo buttons in ArcMap.
    naWindow.StartOperation(naContext)
    
    ' Turning on DelayEvents stops the NAWindow from responding to system events, until it is turned back on.
    ' This will hold off on updating NALocationObjects in the window, helping the system be more responsive during solve.
    naWindow.DelayEvents(Nothing, True)
    
    Try
    naSolver.Solve(naContext, New ESRI.ArcGIS.Geodatabase.GPMessagesClass(), trackCancel)
    naWindow.Message = "Solve completed"
    
    ' Stop the operation. The message passed in shows on the Undo button.
    naWindow.StopOperation(naContext, "Solve")
    Catch e As System.Exception
    ' User aborted this by choice, roll it back.
    If e.Message = "Solve operation cancelled by user." OrElse Not trackCancel.[Continue]() Then
        naWindow.Message = e.Message
        
        ' AbortOperation will stop and automatically undo the current operation.
        naWindow.AbortOperation(naContext)
    Else
        naWindow.StopOperation(naContext, "Solve")
        naWindow.Message = "Error: " & e.Message
    End If
    End Try
    ' Resume listening to events.
    naWindow.DelayEvents(Nothing, False)
    
    ' Notify clients that the context has changed.
    Dim naContextEdit = TryCast(naContext, ESRI.ArcGIS.NetworkAnalyst.INAContextEdit)
    naContextEdit.ContextChanged()
    
    ' Update the NAWindow to have the latest contents.
    naWindow.UpdateContent(Nothing)
End Sub