Set<String> caseInsensitiveSet = new CaseInsensitiveSet<>();

// Java 21 Sequenced Collections support
SequencedCollection<String> sequenced = CollectionsUtil.newLinkedHashSet();
String first = CollectionsUtil.getFirst(sequenced);
String last = CollectionsUtil.getLast(sequenced);
SequencedCollection<String> reversed = CollectionsUtil.reversed(sequenced);

// Specialized collections

  private var mostRecentRebuildFailed: Boolean = false

  /**
   * To differentiate between old and current snapshots, each entry is given a sequence number each
   * time an edit is committed. A snapshot is stale if its sequence number is not equal to its
   * entry's sequence number.
   */
  private var nextSequenceNumber: Long = 0

  private val cleanupQueue = taskRunner.newQueue()
  private val cleanupTask =

        // Test failed casting from sequence
        ASN1EncodableVector vector = new ASN1EncodableVector();
        vector.add(new ASN1Integer(10));
        ASN1Sequence sequence = new DERSequence(vector);
        assertThrows(PACDecodingException.class, () -> {
            ASN1Util.as(ASN1Boolean.class, sequence, 0);
        }, "Should throw PACDecodingException for incompatible types in sequence");
    }

    @LazyInit @Nullable Thread submitting;

    private TaskNonReentrantExecutor(Executor delegate, ExecutionSequencer sequencer) {
      super(NOT_RUN);
      this.delegate = delegate;
      this.sequencer = sequencer;
    }

    @Override
    public void execute(Runnable task) {
      // If this operation was successfully cancelled already, calling the runnable will be a noop.

    }

    @Test
    @DisplayName("byte[] ctor: top-level non-SEQUENCE triggers PACDecodingException (type mismatch)")
    void byteArrayConstructor_topLevelNotSequence_throws() throws Exception {
        // Arrange: Encoded INTEGER instead of SEQUENCE
        byte[] notASequence = new ASN1Integer(42).getEncoded();

        // Act + Assert

        }

        ASN1Sequence sequence;
        try {
            try (ASN1InputStream stream = new ASN1InputStream(new ByteArrayInputStream(token))) {
                sequence = ASN1Util.as(ASN1Sequence.class, stream);
            }
        } catch (IOException e) {
            throw new PACDecodingException("Malformed Kerberos Ticket", e);
        }
        return sequence;
    }

    /**

        this.registrationId = registrationId;
    }

    /**
     * Gets the sequence number.
     *
     * @return the sequence number
     */
    public long getSequenceNumber() {
        return sequenceNumber;
    }

    /**
     * Sets the sequence number.
     *
     * @param sequenceNumber the sequence number
     */
    public void setSequenceNumber(long sequenceNumber) {

        self,
        errors: Sequence[Any],
        *,
        body: Any = None,
        endpoint_ctx: Optional[EndpointContext] = None,
    ) -> None:
        super().__init__(errors, endpoint_ctx=endpoint_ctx)
        self.body = body


class WebSocketRequestValidationError(ValidationException):
    def __init__(
        self,
        errors: Sequence[Any],
        *,

    @LazyInit @Nullable Thread submitting;

    private TaskNonReentrantExecutor(Executor delegate, ExecutionSequencer sequencer) {
      super(NOT_RUN);
      this.delegate = delegate;
      this.sequencer = sequencer;
    }

    @Override
    public void execute(Runnable task) {
      // If this operation was successfully cancelled already, calling the runnable will be a noop.

     * @param sequence the DLSequence
     * @param index the element index
     * @return sequence element cast to type
     * @throws PACDecodingException if types are incompatible
     */
    public static <T extends ASN1Primitive> T as(final Class<T> type, final DLSequence sequence, final int index)
            throws PACDecodingException {
        return as(type, sequence, index);
    }

    /**