src/vs/workbench/services/extensions/common/extensionManifestPropertiesService.ts/ExtensionManifestPropertiesService/toArray
class ExtensionManifestPropertiesService:	private toArray(extensionKind: ExtensionKind | ExtensionKind[]): ExtensionKind[] {
		if (Array.isArray(extensionKind)) {
			return extensionKind;
		}
		return extensionKind === 'ui' ? ['ui', 'workspace'] : [extensionKind];
	}