void IWatermarkCollection.RemoveWatermark(IWatermark watermark)
 {
     WatermarkCollectionUtil.RemoveWatermark(this.Watermarks, watermark);
 }
 IWatermark IWatermarkCollection.AddWatermark(IWatermarkDefinition watermark)
 {
     return(WatermarkCollectionUtil.AddWatermark(this.Watermarks, watermark));
 }