@param [String] name @param [Object] payload @param [Array] parent_names @param [Object] requirement the requirement that is
requiring the child @return [void]
# File lib/rubygems/resolver/molinillo/lib/molinillo/dependency_graph.rb, line 145
def add_child_vertex(name, payload, parent_names, requirement)
root = !parent_names.delete(nil) { true }
vertex = add_vertex(name, payload, root)
vertex.explicit_requirements << requirement if root
parent_names.each do |parent_name|
parent_node = vertex_named(parent_name)
add_edge(parent_node, vertex, requirement)
end
vertex
end