Object readResolve() {
      ImmutableMultiset.Builder<Object> builder =
          new ImmutableMultiset.Builder<Object>(elements.length);
      for (int i = 0; i < elements.length; i++) {
        builder.addCopies(elements[i], counts[i]);
      }
      return builder.build();
    }

    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;
  }

  @Override
  @J2ktIncompatible

            addCalls.incrementAndGet();
            return super.add(element, occurrences);
          }
        };
    ImmutableMultiset<String> adds =
        new ImmutableMultiset.Builder<String>().addCopies("x", 10).build();
    multiset.addAll(adds);
    assertEquals(1, addCalls.get());
  }

  public void testRemoveUnsupported() {
    Multiset<String> multiset = new NoRemoveMultiset<>();
    multiset.add("a");