The default/core payment gateways in Magento 2 check if the user has accepted the terms of service before allowing checkout.

There is a sample payment gateway here for Magento 2: https://github.com/magento/magento2-samples/tree/master/sample-module-payment-gateway

It doesn't implement the terms of service validation and even if they are activated, they are not displayed for this payment gateway => the user can checkout without agreeing with the TOS.

There is some doc about field validators but nothing about the TOS validation in particular. The TOS checkbox is a bit different from other fields as it doesn't seem to be created in the module template files.

How is the TOS validation supposed to be implemented in a custom payment gateway?

The default/core payment gateways in Magento 2 check if user has accepted terms of service before allowing checkout.

There is a sample payment gateway here for Magento 2: https://github.com/magento/magento2-samples/tree/master/sample-module-payment-gateway

It doesn't implement terms of service validation and even if they are activated, they are not displayed for this payment gateway => the user can checkout without agreeing with the TOS.

There is some doc about field validators but nothing about the TOS validation in particular. The TOS checkbox is a bit different from other fields as it doesn't seem to be created in the module template files.

How is the TOS validation supposed to be implemented in a custom payment gateway?