src/vs/workbench/api/browser/mainThreadDocumentsAndEditors.ts/DocumentAndEditorStateDelta/constructor
class DocumentAndEditorStateDelta:	constructor(
		readonly removedDocuments: ITextModel[],
		readonly addedDocuments: ITextModel[],
		readonly removedEditors: TextEditorSnapshot[],
		readonly addedEditors: TextEditorSnapshot[],
		readonly oldActiveEditor: string | null | undefined,
		readonly newActiveEditor: string | null | undefined,
	) {
		this.isEmpty = this.removedDocuments.length === 0
			&& this.addedDocuments.length === 0
			&& this.removedEditors.length === 0
			&& this.addedEditors.length === 0
			&& oldActiveEditor === newActiveEditor;
	}