Bug 148626 [Regression]Can't fetch value from the filter of table/chart which inherites data from container
Steps: 1. create a table and bind a dataset in it 2. create another table/chart in the table detail/table group header 3. switch to the Filter tab in property editor 4. create a filter and select value in "<select value...>" combo 5. an error popuped up, "The expression value can't be retrieved"
chart/org.eclipse.birt.chart.reportitem.ui/src/org/eclipse/birt/chart/reportitem/ui/ReportDataServiceProvider.java
needClean = true;
					needAddBinding = true;
				}
			}
			if ( needClean )
			{
				
				itemHandle.getPropertyHandle( ReportItemHandle.PARAM_BINDINGS_PROP )
						.clearValue( );
				itemHandle.getPropertyHandle( ExtendedItemHandle.FILTER_PROP )
						.clearValue( );
				itemHandle.getColumnBindings( ).clearValue( );
			}
			if ( needAddBinding )
			{
				
				List columnList = generateComputedColumns( itemHandle );
				if ( columnList.size( ) > 0 )
				{
					for ( Iterator iter = columnList.iterator( ); iter.hasNext( ); )
					{
						DEUtil.addColumn( itemHandle,
								(ComputedColumn) iter.next( ),
								false );
					}
				}
			}
		}