src/vs/workbench/contrib/welcome/common/viewsWelcomeContribution.ts/parseGroupAndOrder
function parseGroupAndOrder(welcome: ViewWelcome, contribution: IExtensionPointUser<ViewsWelcomeExtensionPoint>): { group: string | undefined, order: number | undefined } {

	let group: string | undefined;
	let order: number | undefined;
	if (welcome.group) {
		if (!contribution.description.enableProposedApi) {
			contribution.collector.warn(nls.localize('ViewsWelcomeExtensionPoint.proposedAPI', "The viewsWelcome contribution in '{0}' requires 'enableProposedApi' to be enabled.", contribution.description.identifier.value));
			return { group, order };
		}

		const idx = welcome.group.lastIndexOf('@');
		if (idx > 0) {
			group = welcome.group.substr(0, idx);
			order = Number(welcome.group.substr(idx + 1)) || undefined;
		} else {
			group = welcome.group;
		}
	}
	return { group, order };
}