Bug 149922 Image builder - URI and file source type are treated as same
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/ImageHandle.java
* <li><code>IMAGE_REF_TYPE_EMBED</code>
	 * </ul>
	 * 
	 * @return the image source type.
	 * 
	 */
	public String getSource( )
	{
		return getStringProperty( ImageItem.SOURCE_PROP );
	}
	/**
	 * Sets the image source type. This is one of the following options defined
	 * in <code>DesignChoiceConstants</code>:
	 * <p>
	 * <ul>
	 * <li><code>IMAGE_REF_TYPE_NONE</code>
	 * <li><code>IMAGE_REF_TYPE_URL</code>
	 * <li><code>IMAGE_REF_TYPE_FILE</code>
	 * <li><code>IMAGE_REF_TYPE_EXPR</code>
	 * <li><code>IMAGE_REF_TYPE_EMBED</code>
	 * </ul>
	 * 
	 * @param source
	 *            the image source type.
	 * @throws SemanticException
	 *             if the <code>source</code> is not one of the above.
	 * 
	 */
	public void setSource( String source ) throws SemanticException
	{