code: public static void registerSerializers(final Kryo kryo) {
  
          // ImmutableTable (abstract class)
          //  +- SparseImmutableTable
          //  |   SparseImmutableTable
          //  +- DenseImmutableTable
          //  |   Used when more than half of the cells have values
          //  +- SingletonImmutableTable
          //  |   Optimized for Table with only 1 element.
  
          final ImmutableTableSerializer serializer = new ImmutableTableSerializer();
  
          kryo.register(ImmutableTable.class, serializer); // ImmutableTable
          kryo.register(ImmutableTable.of().getClass(), serializer); // SparseImmutableTable
          kryo.register(ImmutableTable.of(1, 2, 3).getClass(), serializer);  // SingletonImmutableTable
  
          kryo.register(ImmutableTable.builder()
                  .put("a", 1, 1)
                  .put("b", 1, 1)
                  .build().getClass(), serializer); // DenseImmutableTable
  
      }
docs: Creates a new {@link ImmutableTableSerializer} and registers its serializer.
  
  @param kryo the {@link Kryo} instance to set the serializer on