final MavenGroupRepository repository = repositories().create(MavenGroupRepository.class, id)
.ofRepositories("central", "releases", "snapshots");
assertThat(repository.memberRepositories(), contains("central", "releases", "snapshots"));
repository.ofRepositories("central", "releases");
assertThat(repository.memberRepositories(), contains("central", "releases"));
repository.addMember("snapshots");
assertThat(repository.memberRepositories(), contains("central", "releases", "snapshots"));