Clarification of "instrumentKey" language

[madmath]

It is my understanding that "instrumentKey" is not going to be set equally by all implementers as part of the "paymentrequest" event.

self.addEventListener('paymentrequest', function(e) {
// e.instrumentKey may or may not be set.
});

The current draft text says:

The instrumentKey identifier will be passed to the payment handler to indicate the PaymentInstrument selected by the user, if any.

I can see how "if any" may indicate that instrumentKey may not be set, but I would recommend language such as "the instrumentKey identifier may be passed if a specific PaymentInstrument has been selected by the user".

cc @rsolomakhin

[rsolomakhin]

Resolved in a pull request. Empty string means that user has not selected an instrument.