src/vs/workbench/contrib/notebook/browser/services/notebookKernelHistoryServiceImpl.ts/NotebookKernelHistoryService/_serialize
class NotebookKernelHistoryService:	private _serialize(): ISerializedKernelsList {
		const result: ISerializedKernelsList = Object.create(null);

		for (const [viewType, kernels] of Object.entries(this._mostRecentKernelsMap)) {
			result[viewType] = {
				entries: [...kernels.values()]
			};
		}
		return result;
	}