Steklov spectral determination conjecture for cuboids

Let a cuboid be a Euclidean rectangular box, and let two cuboids be Steklov isospectral when their Steklov spectra, counted with multiplicities, coincide. Steklov spectral determination conjecture. Any two Steklov isospectral cuboids are isometric. This would extend the paper's result that Steklov isospectral rectangles are isometric; whether nonisometric Steklov isospectral Euclidean domains exist remains unknown.