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
mapQueryToReportItem = queryBuilder.getQueryToReportItemMap( );
		
		
		loadResultSetMetaData( );
		assert mapQueryIDToResultSetName != null;
		
		if (mapQueryToId == null) {
			mapQueryToId = new HashMap();
		}
		mapQueryToId.putAll(report.getQueryIDs());
		 
		
		if (mapDispNameToResultSetName == null)
		{
			mapDispNameToResultSetName = new HashMap();
		}
		else
		{
			mapDispNameToResultSetName.clear( );
		}
		
		
		if( mapDispNameToQuery == null )
		{
			mapDispNameToQuery = new HashMap( );
		}
		else
		{
			mapDispNameToQuery.clear( );
		}