public String getPhone() {
        return this.devices
            .stream()
            .filter(device -> StringUtils.equalsIgnoreCase(device.getType(), "phone")
                || StringUtils.equalsIgnoreCase(device.getType(), "mobile"))
            .map(DuoSecurityUserDevice::getNumber)
            .filter(StringUtils::isNotBlank)
            .findFirst()
            .orElse(StringUtils.EMPTY);
        
    }
Add attribute.

@param key   the key
@param value the value
@return the duo security user account
support/cas-server-support-duo-core-mfa/src/main/java/org/apereo/cas/adaptors/duo/DuoSecurityUserAccount.java