Bug 138828 Export data column are disordered
Steps to reproduce: 1.Add a sample data source and a data set with table "CUSTOMERS" 2.Preview in Web Viewer 3.Click "Export data", choose columns "CUSTOMERNAME","PHONE","CITY","STATE" to be exported, click "OK" Expected result: The exported columns is alphabetic order or the same order as selected columns Actual result: The exported columns is disordered. they are "STATE","CITY","CUSTOMERNAME","PHONE".
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/service/api/IViewerReportService.java
* @param options
	 * @param out
	 * @throws ReportServiceException
	 */
	void extractResultSet( String docName, String resultSetId, Set columns,
			Set filters, InputOptions options, OutputStream out )
			throws ReportServiceException;
	/**
	 * Get the metadata for the result sets
	 * 
	 * @param docName
	 * @param options
	 * @return
	 * @throws ReportServiceException
	 */
	List getResultSetsMetadata( String docName, InputOptions options )
			throws ReportServiceException;
	/**
	 * 
	 * @param docName
	 * @param instanceId
	 * @param options
	 * @return
	 * @throws ReportServiceException
	 */
	List getResultSetsMetadata( String docName, String instanceId,
			InputOptions options ) throws ReportServiceException;
	/**
	 * Render an image to the OutputStream
	 *