Bug 184762 BIRT Model - Enhancments to the level defintion
xtab/org.eclipse.birt.report.item.crosstab.core/src/org/eclipse/birt/report/item/crosstab/core/de/LevelViewHandle.java
public CrosstabCellHandle getCell( )
	{
		PropertyHandle propHandle = getMemberProperty( );
		return propHandle.getContentCount( ) == 0 ? null
				: (CrosstabCellHandle) CrosstabUtil.getReportItem( propHandle.getContent( 0 ),
						CROSSTAB_CELL_EXTENSION_NAME );
	}
	/**
	 * Gets the aggregation header cell of this level view.
	 * 
	 * @return aggregation header cell if set, otherwise null
	 */
	public CrosstabCellHandle getAggregationHeader( )
	{
		PropertyHandle propHandle = getAggregationHeaderProperty( );
		return propHandle.getContentCount( ) == 0 ? null
				: (CrosstabCellHandle) CrosstabUtil.getReportItem( propHandle.getContent( 0 ),
						CROSSTAB_CELL_EXTENSION_NAME );
	}
	/**
	 * Adds a aggregation header to the level if it is empty. This method only
	 * adds the aggreation header cell in this level. It does not adjust any
	 * measure aggreations automatically. User himself needs to add measure
	 * aggregations manually.
	 * 
	 * @deprecated For internal test only, user addSubTotal() instead
	 */
	public void addAggregationHeader( ) throws SemanticException
	{
		if ( getAggregationHeaderProperty( ).getContentCount( ) != 0 )