buildProviderLineItems<Item>(order: PricedOrder,currency: string,render: { line: (line: PricedLine,currency: string,) => Item; extra: (extra: ExtraLine,currency: string,) => Item; },): Item[]
Render a priced order into a provider's line-item array: each ticket line via
line, each extra (booking fee, …) via extra. Providers supply the two
shape callbacks; the ordering (tickets, then extras) matches what Stripe and
Square built by hand before.
Item[]