addAll method
inherited
    This operation is not supported by an unmodifiable list.
Implementation
void addAll(Iterable<E> iterable) {
  throw new UnsupportedError("Cannot add to an unmodifiable list");
}This operation is not supported by an unmodifiable list.
void addAll(Iterable<E> iterable) {
  throw new UnsupportedError("Cannot add to an unmodifiable list");
}