Bug 208412 Enhance Chart Engine to process grouped, uni-dimensional Data
chart/org.eclipse.birt.chart.reportitem/src/org/eclipse/birt/chart/reportitem/ChartReportItemPresentationBase.java
/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.engine.extension.IReportItemPresentation#getImageMIMEType()
	 */
	public String getImageMIMEType( )
	{
		return idr.getMimeType( );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.engine.extension.IReportItemPresentation#getOutputContent()
	 */
	public Object getOutputContent( )
	{
		return null;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.engine.extension.IReportItemPresentation#finish()
	 */
	public void finish( )
	{
		logger.log( ILogger.INFORMATION,
				Messages.getString( "ChartReportItemPresentationImpl.log.finishStart" ) ); 
		
		try
		{