Opinion of Advocate General Sharpston delivered on 29 July 2019.#Cargill Deutschland GmbH v Hauptzollamt Krefeld.#Request for a preliminary ruling from the Finanzgericht Düsseldorf.#Reference for a preliminary ruling — Regulation (EU) No 1360/2013 — Agriculture — Common organisation of the markets — Sugar sector — Production levy — Effectiveness — Right to reimbursement of sums unduly paid — Applicability of national rules on limitation periods — Principle of effectiveness.#Case C-360/18.