This simplifies calculating the overall invoice by giving RESTORE fees a
period equal to the period of the associated RENEW (1 year). Older
BillingEvents will not be backfilled, and will have periodYears = null.
Invoicing and business both agree this is a valid representation, since RESTORE fees are intrinsically tied to the 1-year RENEW it's associated with.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=188041777