Bug 140395 IImage.getID() return null on chart images
When I use image.getID() to retrieve ID of chart image, it always returns null.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/Image.java
{
	protected static Logger logger = Logger.getLogger( Image.class.getName( ) );
	/**
	 * image ID
	 */
	protected String id = null;
	/**
	 * postfix of image
	 */
	protected String extension = null;
	/**
	 * image source
	 */
	protected int source = IImage.INVALID_IMAGE;
	/**
	 * Comment for <code>data</code>
	 */
	protected byte[] data = null;
	/**
	 * Constructor with an image uri
	 * 
	 * @param uri