Failure of a contractor, or of an agent of a contractor, to pay or cause to be paid, in full or pro rata, the lawful claims of all persons, firms, association of persons or corporations (including surveyors and engineers), furnishing labor or material (including fuel), as required by § 3503 of this title, within 30 days after the receipt of any moneys or funds for the purposes of § 3502 of this title, shall be prima facie evidence of the payment, use or appropriation of such trust moneys or funds by the contractor in violation of the provisions of this chapter.