@!visibility private @see DependencyGraph#detach_vertex_named
A vertex in a {DependencyGraph} that encapsulates a {#name} and a {#payload}
Makes a list of existing constants deprecated.
returns an integer in (-infty, 0] a number closer to 0 means the dependency is less constraining
dependencies w/ 0 or 1 possibilities (ignoring version requirements) are given very negative values, so they always sort first, before dependencies that are unconstrained
Indicated, based on the requested domain, if remote gems should be considered.