cdm/src/main/java/ucar/nc2/AttributeContainerHelper.java
@Override
  public void addAll(Iterable<Attribute> atts) {
    for (Attribute att : atts) addAttribute(att);
  }
@Override
  public void addAll(Iterable<Attribute> atts) {
    for (Attribute att : atts) addAttribute(att);
  }
Add all; replace old if has same name