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
}
	/*
	 * Only ISciptExpression is used as column meta data. 
	 * The highlight expression will be translated into many 
	 * duplicated IConditionalExpressions, which cause many duplicated 
	 * column data be exported.
	 * reference bugzilla 121863
	 */
	private Collection getScriptExpressions ( Collection expressions )
	{
		assert expressions != null;
		if( expressions.size( ) <= 0 )
		{
			return null;
		}
		
		ArrayList scriptedExpressions = new ArrayList ( );
		Iterator iter = expressions.iterator( );
		while( iter.hasNext( ) )
		{
			IBaseExpression baseExpr = ( IBaseExpression )iter.next( );
			if( baseExpr instanceof IScriptExpression )
			{
				scriptedExpressions.add( baseExpr );
			}
		}
		return scriptedExpressions;
	}
}