In the 2025 version of the Documents packages, "TimeSpan? timeout" were added to a number of interfaces, with the old versions obsoleted, for example: IWorkbookFormatProvider.Import & IWorkbookFormatProvider.Export.

This is a very strange choice, because this limits the flexibility of the interfaces for no reason at all. By only providing the TimeSpan parameter and not a CancellationToken is currently impossible to cancel the operation because e.g. an API request was canceled.

Internally these methods are implemented by first creating a cancellation token using

using CancellationTokenSource cancellationTokenSource = CancelationTokenSourceFactory.CreateTokenSource(timeout);

the token from this CancellationTokenSource is then passed to a protected method. Because this internal method uses a CancellationToken anyway, there is practically 0 development cost to exposing this in the interface, which makes the choice not to do so even more confusing.

The interfaces should expose methods that take a CancellationToken instead of a TimeSpan. This would allow for the same functionality as the TimeSpan parameter, by simply passing a cancellation token with a CancelAfter set with a TimeSpan, and an extension method could be provided for the interface which does exactly that, so users can still call these methods with a TimeSpan parameter if they wish to do so for convenience.

Please, in the next version, make these interfaces methods like this:

Workbook Import(Stream input, CancellationToken cancellationToken = default);
void Export(Workbook workbook, Stream output, CancellationToken cancellationToken = default);

and, for convenience, add extension methods for these like this:

public static class WorkbookFormatProviderExtensions
{
    public static Workbook Import(this IWorkbookFormatProvider workbookFormatProvider, Stream input, TimeSpan? timeout)
    {
        using CancellationTokenSource cancellationTokenSource = CancelationTokenSourceFactory.CreateTokenSource(timeout);
        return workbookFormatProvider.Import(input, cancellationTokenSource.Token);
    }
}

Affected interfaces I've run into so far:

• Telerik.Windows.Documents.Spreadsheet.FormatProviders.IWorkbookFormatProvider
• Telerik.Windows.Documents.Common.FormatProviders.IFormatProvider<T>

There may be more with this same pattern, I haven't checked.