static <A, B> Map<A, B> putAll(Map<A, B> a, Map<? extends A,? extends B> b) {
  if (a != null && b != null) a.putAll(b);
  ret a;
}

ifclass MultiMap
static <A, B> MultiMap<A, B> putAll(MultiMap<A, B> a, Map<? extends A,? extends B> b) {
  if (a != null) a.putAll(b);
  ret a;
}
endif