(1) The possessor may require from the owner reimbursement of the necessary outlays made on the thing. However, for the period for which the emoluments remain due to the possessor, the customary maintenance costs are not to be reimbursed to them.
(2) If the possessor, after litigation has become pending or after the beginning of the liability set out in section 990, makes necessary outlays, the duty of the owner to reimburse is governed by the provisions on voluntary agency without specific authorisation.