This method is only available on newer versions.
The first available version (v2_6_3) is shown here.
add_vertex(name, payload, root = false)
public
Adds a vertex with the given name, or updates the existing one. @param [String] name @param [Object] payload @return [Vertex] the
vertex that was added to `self`
# File lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph.rb, line 161
def add_vertex(name, payload, root = false)
log.add_vertex(self, name, payload, root)
end