The SecretsManager.getSecretValue method should return an object with signature:
* @param data {Object} The de-serialized data returned from the request. Set to <tt>null</tt> if a request error occurs.
* @param data.ARN {String} The ARN of the secret.
* @param data.Name {String} The friendly name of the secret.
* @param data.VersionId {String} The unique identifier of this version of the secret.
* @param data.SecretBinary {Buffer|TypedArray|Blob|String} The decrypted part of the protected secret information that was originally provided as binary data in the form of a byte array.
But instead of an object, it returns a string that containts the stringified Json object.