if (USE_LEGACY_SERIALIZATION) {
        Object[] keys = new Object[map.size()];
        Object[] values = new Object[map.size()];
        int i = 0;
        // "extends Object" works around https://github.com/typetools/checker-framework/issues/3013
        for (Entry<? extends Object, ? extends Object> entry : map.entrySet()) {
          keys[i] = entry.getKey();
          values[i] = entry.getValue();