src/vs/workbench/contrib/notebook/common/model/notebookTextModel.ts/NotebookTextModel/_changeCellInternalMetadataPartial
class NotebookTextModel:	private _changeCellInternalMetadataPartial(cell: NotebookCellTextModel, internalMetadata: NullablePartialNotebookCellInternalMetadata) {
		const newInternalMetadata: NotebookCellInternalMetadata = {
			...cell.internalMetadata
		};
		let k: keyof NotebookCellInternalMetadata;
		for (k in internalMetadata) {
			const value = internalMetadata[k] ?? undefined;
			newInternalMetadata[k] = value as any;
		}

		cell.internalMetadata = newInternalMetadata;
		this._pauseableEmitter.fire({
			rawEvents: [{ kind: NotebookCellsChangeType.ChangeCellInternalMetadata, index: this._cells.indexOf(cell), internalMetadata: cell.internalMetadata, transient: true }],
			versionId: this.versionId,
			synchronous: true,
			endSelectionState: undefined
		});
	}