Must the expression ‘the commission lost by the commercial agent,’ within the meaning of Article 17(2)(a), second indent, of Council Directive [86/653/EEC] of 18 December 1986 on the coordination of the laws of the Member States relating to self-employed commercial agents, be interpreted to the effect that such commissions include commissions for the conclusion of contracts which a commercial agent would have entered into had the commercial agency [contract] endured, with the customers that he or she brought the principal or with which he or she significantly increased the volume of business?

If so, subject to what conditions does this conclusion apply to ‘one-off commissions’ for the conclusion of a contract?