static void addAll(Collection c, Iterable b) {
if (c != null && b != null) for (A a : b) c.add(a);
}
static void addAll(Collection c, Collection b) {
if (c != null && b != null) c.addAll(b);
}
static void addAll(Collection c, A... b) {
if (c != null) c.addAll(Arrays.asList(b));
}