/// <summary>
/// Appends a <see cref="Watermark"/> to this instance's <see cref="Watermark"/> collection.
/// </summary>
/// <param name="watermark">The watermark to append.</param>
/// <returns>This instance.</returns>
public Output WithWatermark(Watermark watermark)
{
if (watermark != null)
{
return this.WithWatermarks(new[] {watermark});
}
return this;
}