In the proposal, the merchant can optionally specify an SRC-I (that is included in by the common payment handler).
What is the (error) behavior if the browser cannot reach the SRC-I? Does the payment request fail?
If the SRC-I is indeed optional for the merchant to provide, what is the expected behavior when absent? If this is not an error, what party determines who the SRC-I will be? If it is the SRC system, how does the SRC system communicate that to the payment handler?
In the proposal, the merchant can optionally specify an SRC-I (that is included in by the common payment handler).