# File lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph.rb, line 90
    def add_child_vertex(name, payload, parent_names, requirement)
      vertex = add_vertex(name, payload)
      parent_names.each do |parent_name|
        unless parent_name
          vertex.root = true
          next
        end
        parent_node = vertex_named(parent_name)
        add_edge(parent_node, vertex, requirement)
      end
      vertex
    end