  Extending recent results by Cascales, Kadets, Orihuela and Wingler (2016),
Kadets and Zavarzina (2017), and Zavarzina (2017) we demonstrate that for every
Banach space $X$ and every collection $Z_i, i\in I$ of strictly convex Banach
spaces every non-expansive bijection from the unit ball of $X$ to the unit ball
of sum of $Z_i$ by $\ell_1$ is an isometry.
