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
if( mapResultSetToQuery == null )
		{
			mapResultSetToQuery = new HashMap( );
		}
		else
		{
			mapResultSetToQuery.clear( );
		}
		
		if( mapReportItemToDisplayName == null )
		{
			mapReportItemToDisplayName = new HashMap( );
		}
		else
		{
			mapReportItemToDisplayName.clear( );
		}
		 
		ArrayList queryList = report.getQueries();
		int counter = 0;
		for (int i = 0; i < queryList.size(); i++) {
			IQueryDefinition query = (IQueryDefinition) queryList.get(i);
			assert query != null;
			
			String queryId = (String) mapQueryToId.get(query);
			List resultSetList = (List) mapQueryIDToResultSetName.get(queryId);
			if (resultSetList == null) {
				continue;