A counterexample to a theorem of Bremermann on Shilov boundaries

We give a counterexample to the following theorem of Bremermann on Shilov boundaries: if $D$ is a bounded domain in $\mathbb C^n$ having a univalent envelope of holomorphy, say $\widetilde D$, then the Shilov boundary of $D$ with respect to the algebra $\mathcal A(D)$ coincides with the corresponding one for $\widetilde D$.