Bug 150347 Support binary stream as preview image.
See 144843. We need model to save binary strame as report preview image. Currently, preview image is an external image. Maybe need a type to distinguish preview image type.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/activity/NotificationEvent.java
* 
	 * @return the Delivery path. One of:
	 * 
	 * <ul>
	 * <li>DIRECT</li>
	 * <li>DESCENDENT</li>
	 * <li>STYLE_CLIENT</li>
	 * <li>CONTENTS</li>
	 * </ul>
	 */
	public int getDeliveryPath( )
	{
		return deliveryPath;
	}
	/**
	 * Sets the delivery path. Called by the sender to indicate the context.
	 * 
	 * @param path
	 *            the delivery path to set.
	 */
	public void setDeliveryPath( int path )
	{
		deliveryPath = path;
	}
	/**
	 * Returns the sender: the UI or other application object that caused the
	 * event to be sent. The UI component can use this to avoid responding to
	 * changes that the UI component itself caused.
	 * 
	 * @return the sender.