How to use the n8n-core.UserSettings.getEncryptionKey function in n8n-core

this.app.post('/rest/credentials', ResponseHelper.send(async (req: express.Request, res: express.Response): Promise => {
			const incomingData = req.body;

			// Add the added date for node access permissions
			for (const nodeAccess of incomingData.nodesAccess) {
				nodeAccess.date = this.getCurrentDate();
			}

			const encryptionKey = await UserSettings.getEncryptionKey();
			if (encryptionKey === undefined) {
				throw new Error('No encryption key got found to encrypt the credentials!');
			}

			// Check if credentials with the same name and type exist already
			const findQuery = {
				where: {
					name: incomingData.name,
					type: incomingData.type,
				},
			} as FindOneOptions;

			const checkResult = await Db.collections.Credentials!.findOne(findQuery);
			if (checkResult !== undefined) {
				throw new ResponseHelper.ResponseError(`Credentials with the same type and name exist already.`, undefined, 400);
			}

export async function getBase(credentials: IWorkflowCredentials, currentNodeParameters: INodeParameters[] = []): Promise {
	const urlBaseWebhook = WebhookHelpers.getWebhookBaseUrl();

	const timezone = config.get('generic.timezone') as string;
	const webhookBaseUrl = urlBaseWebhook + config.get('endpoints.webhook') as string;
	const webhookTestBaseUrl = urlBaseWebhook + config.get('endpoints.webhookTest') as string;

	const encryptionKey = await UserSettings.getEncryptionKey();
	if (encryptionKey === undefined) {
		throw new Error('No encryption key got found to decrypt the credentials!');
	}

	return {
		credentials,
		encryptionKey,
		executeWorkflow,
		restApiUrl: urlBaseWebhook + config.get('endpoints.rest') as string,
		timezone,
		webhookBaseUrl,
		webhookTestBaseUrl,
		currentNodeParameters,
	};
}