/*
   * This class is used to serialize all ImmutableSortedSet instances,
   * regardless of implementation type. It captures their "logical contents"
   * only. This is necessary to ensure that the existence of a particular
   * implementation type is an implementation detail.
   */
  @J2ktIncompatible // serialization
  private static class SerializedForm<E> implements Serializable {

    public ImmutableSet<@NonNull E> immutableCopy() {
      return ImmutableSet.copyOf((SetView<@NonNull E>) this);
    }

    /**
     * Copies the current contents of this set view into an existing set. This method has equivalent
     * behavior to {@code set.addAll(this)}, assuming that all the sets involved are based on the
     * same notion of equivalence.
     *

   * ImmutableEnumSet/ImmutableSortedSet, regardless of implementation type. It
   * captures their "logical contents" and they are reconstructed using public
   * static factories. This is necessary to ensure that the existence of a
   * particular implementation type is an implementation detail.
   */
  @J2ktIncompatible // serialization
  private static class SerializedForm implements Serializable {
    final Object[] elements;

   * put()} and {@code putAll()} methods throw an {@link IllegalArgumentException}. Similarly, the
   * map's entries have a {@link Entry#setValue} method that throws an {@link
   * IllegalArgumentException} when the existing key and the provided value don't satisfy the
   * predicate.
   *
   * <p>When methods such as {@code removeAll()} and {@code clear()} are called on the filtered map