src/vs/workbench/contrib/notebook/common/notebookEditorModel.ts/ComplexNotebookEditorModel/getUntitledDocumentData
class ComplexNotebookEditorModel:	private async getUntitledDocumentData(resource: URI): Promise<VSBuffer | undefined> {
		// If it's an untitled file we must populate the untitledDocumentData
		const untitledString = this.untitledTextEditorService.getValue(resource);
		let untitledDocumentData = untitledString ? VSBuffer.fromString(untitledString) : undefined;
		return untitledDocumentData;
	}