@Override
  public void putAll(Map<? extends TypeK, ? extends TypeV> m) {
    for (Map.Entry<? extends TypeK, ? extends TypeV> e : m.entrySet())
      put(e.getKey(), e.getValue());
  }
Copies all of the mappings from the specified map to this one, replacing
 any existing mappings.
 @param m mappings to be stored in this map
jctools-core/src/main/java/org/jctools/maps/NonBlockingHashMap.java