src/vs/workbench/common/notifications.ts/NotificationViewItem/equals
class NotificationViewItem:	equals(other: INotificationViewItem): boolean {
		if (this.hasProgress || other.hasProgress) {
			return false;
		}

		if (typeof this.id === 'string' || typeof other.id === 'string') {
			return this.id === other.id;
		}

		if (typeof this._source === 'object') {
			if (this._source.label !== other.source || this._source.id !== other.sourceId) {
				return false;
			}
		} else if (this._source !== other.source) {
			return false;
		}

		if (this._message.raw !== other.message.raw) {
			return false;
		}

		const primaryActions = (this._actions && this._actions.primary) || [];
		const otherPrimaryActions = (other.actions && other.actions.primary) || [];
		return equals(primaryActions, otherPrimaryActions, (action, otherAction) => (action.id + action.label) === (otherAction.id + otherAction.label));
	}