Bug 202254 Exception is thrown when category values are null and type of X axis is set to DateTime
chart/org.eclipse.birt.chart.ui.extension/src/org/eclipse/birt/chart/ui/swt/wizard/format/axis/AbstractAxisSubtask.java
.getCaption( )
					.setFont( fdcFont.getFontDefinition( ) );
			getAxisForProcessing( ).getLabel( )
					.getCaption( )
					.setColor( fdcFont.getFontColor( ) );
		}
	}
	public void widgetSelected( SelectionEvent e )
	{
		
		if ( detachPopup( e.widget ) )
		{
			return;
		}
		if ( isRegistered( e.widget ) )
		{
			attachPopup( ( (Button) e.widget ).getText( ) );
		}
		if ( e.widget.equals( cmbTypes ) )
		{
			final AxisType axisType = AxisType.getByName( LiteralHelper.axisTypeSet.getNameByDisplayName( cmbTypes.getText( ) ) );
			if ( getAxisForProcessing( ).getType( ) == axisType )
			{
				
				return;
			}
			
			ChartAdapter.beginIgnoreNotifications( );
			{
				convertSampleData( axisType );