Bug 193467 URL hyperlink can't work in chart viewer
chart/org.eclipse.birt.chart.viewer/src/org/eclipse/birt/chart/viewer/internal/util/ChartImageManager.java
}
			catch ( Exception ioex )
			{
				throw new ChartException( ChartEnginePlugin.ID,
						ChartException.GENERATION,
						ioex );
			}
			if ( !"SVG".equalsIgnoreCase( sExtension ) && idr instanceof IImageMapEmitter ) 
			{
				imageMap = ( (IImageMapEmitter) idr ).getImageMap( );
			}
		}
		catch ( BirtException birtException )
		{
			Throwable ex = birtException;
			while ( ex.getCause( ) != null )
			{
				ex = ex.getCause( );
			}
			if ( ex instanceof ChartException
					&& ( (ChartException) ex ).getType( ) == ChartException.ZERO_DATASET )
			{
				
				
				return null;
			}
			if ( ex instanceof ChartException
					&& ( (ChartException) ex ).getType( ) == ChartException.ALL_NULL_DATASET )
			{