private static List<String> dependsOn(List<GradleTask> tasks) {
   List<String> names = Lists.newArrayList();
   for (GradleTask task : tasks) {
     names.add(task.getName());
   }
   return names;
 }
 /** Calculates difference between first and second (all first elements minus second). */
 private static <T> List<T> subtract(List<T> first, List<T> second) {
   List<T> result = Lists.newArrayList(first);
   result.removeAll(second);
   return result;
 }