in src/Amazon.Extensions.CognitoAuthentication/CognitoUserAuthentication.cs [491:497]
private string GetChallengeParamCodeName(ChallengeNameType challengeNameType )
{
if (challengeNameType == ChallengeNameType.SMS_MFA) return CognitoConstants.ChlgParamSmsMfaCode;
if (challengeNameType == ChallengeNameType.SOFTWARE_TOKEN_MFA) return CognitoConstants.ChlgParamSoftwareTokenMfaCode;
return null;
}