Bug 182895 Support sort on Level attribute.
Currently in OLAP engine we only support sort on level key value. We should go ahead to support sort on level attribute value.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/olap/data/api/CubeQueryExecutorHelper.java
/**
	 * 
	 * @return sortDefinition list on column edge
	 */
	public List getColumnSort( )
	{
		return this.columnSort;
	}
	
	/**
	 * 
	 * @param sort
	 */
	public void addColumnSort( AggrSortDefinition sort )
	{
		this.columnSort.add( sort );
	}
	
	/*
	 * (non-Javadoc)
	 * @see org.eclipse.birt.data.olap.data.api.ICubeQueryExcutorHelper#addFilter(java.lang.String, org.eclipse.birt.data.olap.data.api.ISelection[])
	 */
	public void addFilter( LevelFilter levelFilter )
	{		
		levelFilters.add( levelFilter );
	}
	
	/*
	 * (non-Javadoc)