  Consider a finite dimensional vector space $V$ over a finite field
$\mathbb{F}_q$. We give a minimal generating set for the ring of invariants
$\mathbb{F}_q[V \oplus V^*]^{\text{GL}(V)}$, and show that this ring is a
Gorenstein ring but is not a complete intersection. These results confirm a
conjecture of Bonnaf\'e and Kemper.
