Godsil's edge-connectivity conjecture for colour classes in association schemes

Let an association scheme be a finite set equipped with relations whose colour classes are the graphs arising from the corresponding adjacency matrices. For a graph $G$, let $\lambda(G)$ denote its edge-connectivity, and let its degree mean its regular vertex degree.

Godsil's conjecture. If $G$ is a connected graph which is a colour class in an association scheme, then

$$\lambda(G)=\text{degree of }G.$$

The conjecture is solved in the source: the authors prove that every connected regular equiarboreal graph has edge-connectivity equal to its degree, and colour classes in association schemes are equiarboreal and regular.