Bug 168026 Still use the existing data binding even though the aggregate is different
I had a table in which a data binding which aggregates on a group. When I insert a new data item in the report, although the expressions are same, it aggregates on All, then it refered to the existing data binding. The expected behavior would be a new data binding is created with different aggregates.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/ReportItemHandle.java
TOC toc = (TOC) propHandle.getValue( );
		if ( toc == null )
			return null;
		return (TOCHandle) toc.getHandle( propHandle );
	}
	/**
	 * Adds toc structure.
	 * 
	 * @param expression
	 *            toc expression
	 * @return toc handle
	 * @throws SemanticException
	 */
	public TOCHandle addTOC( String expression ) throws SemanticException
	{
		if ( StringUtil.isEmpty( expression ) )
			return null;
		TOC toc = StructureFactory.createTOC( expression );
		setProperty( IReportItemModel.TOC_PROP, toc );
		return (TOCHandle) toc
				.getHandle( getPropertyHandle( IReportItemModel.TOC_PROP ) );
	}
	/**
	 * Adds toc structure.
	 * 
	 * @param toc
	 *            toc structure
	 * @return toc handle
	 * @throws SemanticException
	 */