src/vs/workbench/services/environment/electron-sandbox/environmentService.ts/NativeWorkbenchEnvironmentService/extensionEnabledProposedApi
class NativeWorkbenchEnvironmentService:	get extensionEnabledProposedApi(): string[] | undefined {
		if (Array.isArray(this.args['enable-proposed-api'])) {
			return this.args['enable-proposed-api'];
		}

		if ('enable-proposed-api' in this.args) {
			return [];
		}

		return undefined;
	}