code: public static void registerSerializers(final Kryo kryo) {
  
           final MapSerializer serializer = new MapSerializer();
  
           kryo.register(Map.class, serializer);
           kryo.register(Maps.of().getClass(), serializer);
  
           Object o1 = new Object();
           Object o2 = new Object();
           Object o3 = new Object();
           Object o4 = new Object();
           Object o5 = new Object();
  
           kryo.register(Maps.of(o1, o1).getClass(), serializer);
           kryo.register(Maps.of(o1, o1, o2, o2).getClass(), serializer);
           kryo.register(Maps.of(o1, o1, o2, o2, o3, o3).getClass(), serializer);
           kryo.register(Maps.of(o1, o1, o2, o2, o3, o3, o4, o4).getClass(), serializer);
           kryo.register(Maps.of(o1, o1, o2, o2, o3, o3, o4, o4, o5, o5).getClass(), serializer);
  
       }
docs: Creates a new {@link ImmutableMapSerializer} and registers its serializer
  for the several ImmutableMap related classes.
  
  @param kryo the {@link Kryo} instance to set the serializer on