// verb=attest.
  //
  // If signerName is not empty, then the ClusterTrustBundle object must be
  // named with the signer name as a prefix (translating slashes to colons).
  // For example, for the signer name `example.com/foo`, valid
  // ClusterTrustBundle object names include `example.com:foo:abc` and
  // `example.com:foo:v1`.
  //

	for scanner.Scan() {
		token := scanner.Text()
		substrings := strings.SplitN(token, ":", 3)
		if len(substrings) < 3 {
			return nil, fmt.Errorf("cgroup entry contains %v colons, but expected at least 2 colons: %q", len(substrings), token)
		}
		cgroups = append(cgroups, Cgroup{
			HierarchyID:    substrings[0],
			ControllerList: substrings[1],
			GroupPath:      substrings[2],
		})
	}