- GET
/purchase/bills - POST
/purchase/bills - POST
/purchase/bills/{bill_id}/payments/recalc - DELETE
/purchase/bills/{id} - GET
/purchase/bills/{id} - PUT
/purchase/bills/{id} - POST
/purchase/bills/{id}/lock - POST
/purchase/bills/{id}/unlock - GET
/purchase/bills/export/{format} - POST
/purchase/bills/export/{format} - GET
/purchase/bills/payment-reference