A family of Kähler flying wing steady Ricci solitons

In $1996$, H.-D. Cao constructed a $U(n)$-invariant steady gradient Kähler-Ricci soliton on $\mathbb{C}^{n}$ and asked whether every steady gradient Kähler-Ricci soliton of positive curvature on $\mathbb{C}^{n}$ is necessarily $U(n)$-invariant (and hence unique up to scaling). Recently, Apostolov-Ci