Bug 145520 Group name will not show up in group list if the group use default name and key expression has no value
Description: Group name will not show up in group list if key expression has no value. Steps to reproduce: 1. Insert a table into report, bind it to a data set 2. Switch to property editor -> groups 3. Click on add button to open new group dialog, then press ok button Expected result: A new group with default name will be added to group list Actual result: A new group is added to group list, but without group name. But when let group tab lost focus and get focus again, you can see the group name.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/ContentCommand.java
throws ContentException, NameException
	{
		assert content.getContainer( ) == null;
		
		ElementDefn metaData = (ElementDefn) element.getDefn( );
		if ( !metaData.isContainer( ) )
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_NOT_CONTAINER );
		SlotDefn slotInfo = (SlotDefn) metaData.getSlot( slotID );
		if ( slotInfo == null )
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_SLOT_NOT_FOUND );
		if ( !slotInfo.canContain( content ) )
			throw new ContentException( element, slotID, content,
					ContentException.DESIGN_EXCEPTION_WRONG_TYPE );
		
		
		if ( element.isVirtualElement( ) || element.getExtendsName( ) != null )
			throw new ContentException(
					element,
					slotID,
					content,
					ContentException.DESIGN_EXCEPTION_STRUCTURE_CHANGE_FORBIDDEN );
		
		if ( element.isContentOf( content ) )
			throw new ContentException( element, slotID, content,
					ContentException.DESIGN_EXCEPTION_RECURSIVE );
		
		if ( !slotInfo.isMultipleCardinality( )
				&& element.getSlot( slotID ).getCount( ) > 0 )