Bug 145478 Unable "Select Value" in the Join data set's filter
Step to reproduce: 1.new a join data set(please use the attached file) 2.right click the dataset and click the Edit 3.go to the Filter pane and set a filer 4.click the list of Value1 Actual result: A warning pop up and cant select Value.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/data/ui/util/DataSetProvider.java
DataSetViewData[] columns = (DataSetViewData[]) htColumns.get( dataSet );
		
		if ( !refresh && columns == null )
		{
			columns = getCachedColumns( dataSet );
		}
		
		
		if ( columns == null || refresh )
		{
			
			columns = null;
			try
			{
				
				boolean canExecute = true;
				if ( dataSet instanceof OdaDataSetHandle )
				{
					String queryTxt = ( (OdaDataSetHandle) dataSet ).getQueryText( );
					canExecute = ( queryTxt != null && queryTxt.trim( )
							.length( ) > 0 );
				}
				if ( canExecute )
				{
					IQueryResults results = execute( dataSet,
							useColumnHints,
							true,
							1 );
					if ( results != null )
					{