Changes to Create a tracking link

added the required property earnings/firstPaymentGross to the response with the 201 status

added the required property earnings/otherSpendGross to the response with the 201 status

added the required property earnings/renewalGross to the response with the 201 status

added the required property engagement/newSubscribers to the response with the 201 status

added the required property engagement/paidSubscribers to the response with the 201 status

added the required property engagement/returningSubscribers to the response with the 201 status

added the required property engagement/trialStarts to the response with the 201 status