Morita equivalence of shifted symplectic Lie n-groupoids

Symplectic structures on higher objects like Lie groupoids have been studied for some time now, but not all of the proposed definitions are preserved under Morita equivalence of Lie groupoids, in turn giving rise to a consistent notion of symplectic stacks. Recently, this concept has been generalized to m-shifted symplectic forms on Lie n-groupoids, which are indeed preserved under Morita equivalence of Lie n-groupoids. In this paper, we give a rigorous proof for this statement.