discovery/marathon/marathon.go
func appsToTargetGroups(apps *appList) map[string]*targetgroup.Group {
	tgroups := map[string]*targetgroup.Group{}
	for _, a := range apps.Apps {
		group := createTargetGroup(&a)
		tgroups[group.Source] = group
	}
	return tgroups
}
func appsToTargetGroups(apps *appList) map[string]*targetgroup.Group {
	tgroups := map[string]*targetgroup.Group{}
	for _, a := range apps.Apps {
		group := createTargetGroup(&a)
		tgroups[group.Source] = group
	}
	return tgroups
}
// appsToTargetGroups takes an array of Marathon apps and converts them into target groups.