Complex symmetric composition operators

Let $\varphi$ be a linear fractional self-map of the open unit disk $\mathbb{D}$ and $H^2$ the Hardy space of analytic functions on $\mathbb{D}$. The goal of this article is to characterize the linear fractional composition operators $C_\varphi f=f\circ\varphi$ on $H^2$ that are complex symmetric.