Bug 122854 There is redundant columns in "available columns" list in "export data" dialog.
Description: There is redundant columns in "available columns" list in "export data" dialog. Steps to reproduce: 1. Preview attached design in web viewer. 2. Select the table and click on "export" button. 3. There is a "detail" column name in "available columns" list which is not data set column.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/DataExtractionTask.java
protected ComponentID componentId;
	
	protected InstanceID instanceId;
	
	protected String[] selectedColumns;
	
	protected Report report;
	
	protected List resultMetaList;
	
	protected IExtractionResults currentResult = null;
	
	/*
	 * map query id to result set name stored in DtE
	 */
	protected HashMap mapQueryIDToResultSetName;
	/*
	 * map query to query ID
	 */
	protected HashMap mapQueryToId;
	/*
	 * current result set name
	 */
	protected String resultSetName;
	/*
	 * map IBaseQueryDefinition to ReportItemDesign, namely TableItemDesign, ListItemDesign
	 * and ExtendedItemDesign
	 */
	protected HashMap mapQueryToReportItem;