stsRoleArn                = "RoleArn"
	stsWebIdentityToken       = "WebIdentityToken"
	stsWebIdentityAccessToken = "WebIdentityAccessToken" // only valid if UserInfo is enabled.
	stsDurationSeconds        = "DurationSeconds"
	stsLDAPUsername           = "LDAPUsername"
	stsLDAPPassword           = "LDAPPassword"
	stsRevokeTokenType        = "TokenRevokeType"

	// STS API action constants
	clientGrants        = "AssumeRoleWithClientGrants"

	if exp == nil || exp.IsZero() || exp.Equal(timeSentinel) {
		return nil
	}
	dur := time.Until(*exp)
	if dur <= 0 {
		return errors.New("unsupported expiration time")
	}
	condValues["DurationSeconds"] = []string{strconv.FormatInt(int64(dur.Seconds()), 10)}
	return nil
}