Change how A* chooses what is solid?

I am useing A* to path find in Unity2d but instead of useing objects in a specific layer as what A* counts as solid is there a way for me to edit the code to pull from a bool[pos.x,pos.y] to check if that location is solid or not? I already have an array of arrays with a spot for every node on the graph, but I cannot seem to figure out what part of the A* script I need to edit to make that the deciding factor for if a spot is solid or not instead of the collision in that location on a set layer.

My a* works on a 2d grid, composed of gridNode structs. Each gridNode has a isWalkable bool. You can just change that to isSolid?