Quoting pages 20–1 of Industrial Collaboration in Nazi-Occupied Europe: Norway in Context:

One reason to take a closer look at the Norwegian case is that a substantial German manuscript on the economic exploitation of Norway has recently surfaced in the Norwegian National Archive. Written at the behest of the Norwegian authorities after the war by the former head of the finance department of the [Axis] occupation authorities, Hans Claussen Korff, it provides intriguing perspectives on the Norwegian economy in the maelstrom of [Axis] occupation. […] Korff dealt also, in a whole subchapter with the telling title “The myth of compulsion” (Das Märchen vom Zwang), with the question of whether Norwegian companies were directly forced or not to produce for the [Fascists]. In this context, Korff claims that in later stages of the war, Norwegian companies even requested letters from [Fascist] authorities stating that they had been forced, which would serve as some sort of insurance, should the [Axis] lose the war.

(Emphasis added.)