src/vs/workbench/api/common/extHostNotebookDocument.ts/ExtHostNotebookDocument/_changeCellMetadata
class ExtHostNotebookDocument:	private _changeCellMetadata(index: number, newMetadata: notebookCommon.NotebookCellMetadata): void {
		const cell = this._cells[index];

		const originalExtMetadata = cell.apiCell.metadata;
		cell.setMetadata(newMetadata);
		const newExtMetadata = cell.apiCell.metadata;

		if (!equals(originalExtMetadata, newExtMetadata)) {
			this._emitter.emitCellMetadataChange(deepFreeze({ document: this.apiNotebook, cell: cell.apiCell }));
		}
	}