@!visibility private (see DependencyGraph#add_edge_no_circular
)
@!visibility private (see DependencyGraph#delete_edge
)
@!visibility private @see DependencyGraph#detach_vertex_named
A vertex in a {DependencyGraph} that encapsulates a {#name} and a {#payload}
Delegates
all {Gem::Resolver::Molinillo::SpecificationProvider} methods to a ‘#specification_provider` property.