src/vs/workbench/contrib/notebook/common/model/notebookCellTextModel.ts/NotebookCellTextModel/_getPersisentMetadata
class NotebookCellTextModel:	private _getPersisentMetadata() {
		let filteredMetadata: { [key: string]: any; } = {};
		const transientCellMetadata = this.transientOptions.transientCellMetadata;

		const keys = new Set([...Object.keys(this.metadata)]);
		for (let key of keys) {
			if (!(transientCellMetadata[key as keyof NotebookCellMetadata])
			) {
				filteredMetadata[key] = this.metadata[key as keyof NotebookCellMetadata];
			}
		}

		return filteredMetadata;
	}