when (val protocol = sslSocket.applicationProtocol) {
        null, "" -> null
        else -> protocol
      }
    } catch (e: UnsupportedOperationException) {
      // https://docs.oracle.com/javase/9/docs/api/javax/net/ssl/SSLSocket.html#getApplicationProtocol--
      null
    }

  override fun trustManager(sslSocketFactory: SSLSocketFactory): X509TrustManager? {

   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public final @Nullable Entry<E> pollFirstEntry() {
    throw new UnsupportedOperationException();
  }

  /**
   * {@inheritDoc}

     *
     * @throws UnsupportedOperationException always
     * @deprecated Unsupported operation.
     */
    @CanIgnoreReturnValue
    @Deprecated
    @Override
    @DoNotCall("Always throws UnsupportedOperationException")
    public final boolean add(@ParametricNullness E e) {
      throw new UnsupportedOperationException();
    }

    /**

    throw new UnsupportedOperationException();
  }

  /**
   * Guaranteed to throw an exception and leave the multimap unmodified.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")

   * the range set that are {@linkplain Range#isConnected(Range) connected} with it. Moreover, if
   * {@code range} is empty, this is a no-op.
   *
   * @throws UnsupportedOperationException if this range set does not support the {@code add}
   *     operation
   */
  void add(Range<C> range);

  /**
   * Removes the specified range from this {@code RangeSet} (optional operation). After this

  public void testRemove_unsupportedPresent() {
    assertThrows(UnsupportedOperationException.class, () -> getMap().remove(k0(), v0()));
    expectUnchanged();
  }

  @MapFeature.Require(absent = SUPPORTS_REMOVE)
  public void testRemove_unsupportedAbsent() {
    try {
      assertFalse(getMap().remove(k0(), v3()));
    } catch (UnsupportedOperationException tolerated) {

  @SuppressWarnings("DoNotCall")
  public void testRemove() {
    Iterator<String> iterator = create();

    assertTrue(iterator.hasNext());
    assertThat(iterator.next()).isEqualTo("a");
    assertThrows(UnsupportedOperationException.class, () -> iterator.remove());
  }

  @SuppressWarnings("DoNotCall")
  public void testAdd() {
    ListIterator<String> iterator = create();

    assertTrue(iterator.hasNext());

  @SuppressWarnings("DoNotCall")
  public void testRemove() {
    Iterator<String> iterator = create();

    assertTrue(iterator.hasNext());
    assertThat(iterator.next()).isEqualTo("a");
    assertThrows(UnsupportedOperationException.class, () -> iterator.remove());
  }

  @SuppressWarnings("DoNotCall")
  public void testAdd() {
    ListIterator<String> iterator = create();

    assertTrue(iterator.hasNext());

  public void testRemove_unsupportedNotPresent() {
    try {
      assertFalse(
          "remove(notPresent) should return false or throw UnsupportedOperationException",
          collection.remove(e3()));
    } catch (UnsupportedOperationException tolerated) {
    }
    expectUnchanged();
    expectMissing(e3());
  }

  @CollectionFeature.Require(value = SUPPORTS_REMOVE, absent = ALLOWS_NULL_QUERIES)

   *
   * @throws UnsupportedOperationException always
   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public final @Nullable Entry<K, V> pollFirstEntry() {
    throw new UnsupportedOperationException();
  }

  /**