In a project with an online dependency management done by ivy/maven, is it good practice to back-up the artifacts e.g. by including them in the projects source code / version control (e.g. svn, git) or is it (safe) enough to so so with pom.xml / ivy.xml? Of course, having the artifacts not backed up somehow makes the project totaly depend on the availability of the maven repo.
EDIT:
The reason for my question is that I fear that certain artifacts are no longer available on the official maven repository, or even that the repository itself is down. In such a case, having the libs under version control gives the security to be able to build the project in such a case.