Bug 121687 Exception throws when export data in table which inside a grid cell.
Description: Exception throws when export data in table which inside a grid cell. Steps to reproduce: 1. insert a grid. 2. insert one table to one grid cell. 3. insert another table to the other grid cell. 4. export data in two tables. Expected result: Data are exported. Actual result: Exception in: ReportEngineService.getMetaData( )
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/parser/EngineIRVisitor.java
{
				ColumnDesign columnDesign = (ColumnDesign) currentElement;
				for ( int j = 0; j < columnHandle.getRepeatCount( ); j++ )
				{
					table.addColumn( columnDesign );
				}
			}
		}
		
		SlotHandle headerSlot = handle.getHeader( );
		TableBandDesign header = createTableBand( headerSlot );
		table.setHeader( header );
		
		SlotHandle groupSlot = handle.getGroups( );
		for ( int i = 0; i < groupSlot.getCount( ); i++ )
		{
			apply( groupSlot.get( i ) );
			if ( currentElement != null )
			{
				table.addGroup( (TableGroupDesign) currentElement );
			}
		}
		
		SlotHandle detailSlot = handle.getDetail( );
		TableBandDesign detail = createTableBand( detailSlot );
		table.setDetail( detail );
		
		SlotHandle footerSlot = handle.getFooter( );
		TableBandDesign footer = createTableBand( footerSlot );
		table.setFooter( footer );