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
TriggerSupportMatrix.TYPE_AXIS,
				false,
				true );
		Button btnInteractivity = createToggleButton( cmp,
				Messages.getString( "SeriesYSheetImpl.Label.Interactivity&" ), 
				popup );
		btnInteractivity.addSelectionListener( this );
		btnInteractivity.setEnabled( getChart( ).getInteractivity( ).isEnable( ) );
	}
	private void populateLists( )
	{
		
		NameSet ns = LiteralHelper.axisTypeSet;
		if ( getAxisAngleType( ) == AngleType.Y )
		{
			
			int indexText = ns.getSafeNameIndex( AxisType.TEXT_LITERAL.getName( ) );
			String[] originalItems = ns.getDisplayNames( );
			String[] newItems = new String[originalItems.length - 1];
			for ( int i = 0, j = 0; i < originalItems.length; i++ )
			{
				if ( i == indexText )
				{
					continue;
				}
				newItems[j++] = originalItems[i];
			}
			cmbTypes.setItems( newItems );
		}
		else