@Override
    public <T> T lookup(Class<T> type, String name) {
        return lookup(type);
    }

    @Override
    public <T> Optional<T> lookupOptional(Class<T> type) {
        return Optional.ofNullable(type.cast(components.get(type)));
    }

    @Override
    public <T> Optional<T> lookupOptional(Class<T> type, String name) {
        return lookupOptional(type);
    }

    @Override

        if (field.getGenericType() == field.getType() && type.isAssignableFrom(field.getType())) {
          field.setAccessible(true);
          try {
            T constant = type.cast(field.get(null));
            if (constant != null) {
              return constant;
            }
          } catch (IllegalAccessException impossible) {
            throw new AssertionError(impossible);
          }

    public HashCode hash() {
      long value = checksum.getValue();
      if (bits == 32) {
        /*
         * The long returned from a 32-bit Checksum will have all 0s for its second word, so the
         * cast won't lose any information and is necessary to return a HashCode of the correct
         * size.
         */
        return HashCode.fromInt((int) value);
      } else {
        return HashCode.fromLong(value);

 * the symmetry of {@code equals}. Custom definitions of equality are usually based on an interface,
 * such as {@code Set} or {@code List}, so that the implementation of {@code equals} can cast the
 * object being tested for equality to the custom interface. {@code ForwardingObject} implements no
 * such custom interfaces directly; they are implemented only in subclasses. Therefore, forwarding

  @CheckForNull private transient volatile CacheEntry<K, V> cacheEntry2;

  MapRetrievalCache(Map<K, V> backingMap) {
    super(backingMap);
  }

  @SuppressWarnings("unchecked") // Safe because we only cast if key is found in map.
  @Override
  @CheckForNull
  V get(Object key) {
    checkNotNull(key);
    V value = getIfCached(key);
    if (value != null) {
      return value;
    }

      int n, @Nullable Entry<K, V>[] entryArray, boolean throwIfDuplicateKeys)
      throws BucketOverflowException {
    /*
     * The cast is safe: n==entryArray.length means that we have filled the whole array with Entry
     * instances, in which case it is safe to cast it from an array of nullable entries to an array
     * of non-null entries.
     */
    @SuppressWarnings("nullness")
    Entry<K, V>[] entries =

 * Optional}</a>.
 *
 * @param <T> the type of instance that can be contained. {@code Optional} is naturally covariant on
 *     this type, so it is safe to cast an {@code Optional<T>} to {@code Optional<S>} for any
 *     supertype {@code S} of {@code T}.
 * @author Kurt Alfred Kluever
 * @author Kevin Bourrillion
 * @since 10.0
 */

      Headers.Builder()
        .addUnsafeNonAscii("header1", "valué1")
        .build()
    assertThat(headers.toString()).isEqualTo("header1: valué1\n")
  }

  // Fails on JS, ClassCastException: Illegal cast
  @Test fun ofMapThrowsOnNull() {
    assertFailsWith<NullPointerException> {
      (mapOf("User-Agent" to null) as Map<String, String>).toHeaders()
    }
  }

  @Test fun toMultimapGroupsHeaders() {

 * https://lauri.võsandi.com/2017/03/yubikey-for-ssh-auth.html
 *
 * Using PKCS11 support in the JDK.
 * https://tersesystems.com/blog/2018/09/08/keymanagers-and-keystores/
 *
 * Install OpenSC separately. On a mac `brew cast install opensc`.
 */
@SuppressSignatureCheck
class YubikeyClientAuth {
  fun run() {
    // The typical PKCS11 slot, may vary with different hardware.
    val slot = 0

   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.filter(type::isInstance).map(type::cast)}.
   * This does perform a little more work than necessary, so another option is to insert an
   * unchecked cast at some later point:
   *
   * <pre>
   * {@code @SuppressWarnings("unchecked") // safe because of ::isInstance check
   * ImmutableList<NewType> result =