The identifier for an MFA device. Either a serial number for hardware MFA devices, or an ARN for virtual devices.
This is only required if the trust policy of the role being assumed includes a condition that requires MFA authentication..
Specify a serial number such as "GAHT12345678" for hardware MFA devices.
Specify an ARN such as "arn:aws:iam::123456789012:mfa/user" for virtual MFA devices.