*/
  open fun onClosed(eventSource: EventSource) {
  }

  /**
   * Invoked when an event source has been closed due to an error reading from or writing to the
   * network. Incoming events may have been lost. No further calls to this listener will be made.
   */
  open fun onFailure(
    eventSource: EventSource,
    t: Throwable?,
    response: Response?,
  ) {
  }

    /** Name of the search engine cluster */
    protected String clusterName = "fesen";

    /** List of rewrite rules for document settings */
    protected final List<UnaryOperator<String>> docSettingRewriteRuleList = new ArrayList<>();

    /** List of rewrite rules for document mappings */
    protected final List<UnaryOperator<String>> docMappingRewriteRuleList = new ArrayList<>();

    assertAssignable(
        new TypeToken<List<? extends N1>>() {}, new TypeToken<List<? extends N1>>() {});
    assertAssignable(new TypeToken<List<? super N1>>() {}, new TypeToken<List<? super N1>>() {});
    assertAssignable(
        new TypeToken<List<? extends Number>>() {}, new TypeToken<List<? extends Number>>() {});
    assertAssignable(
        new TypeToken<List<? super Number>>() {}, new TypeToken<List<? super Number>>() {});
  }

// Enhanced collection creation
List<String> list = CollectionsUtil.newArrayList();
Map<String, Object> map = CollectionsUtil.newLinkedHashMap();
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);

    assertAssignable(
        new TypeToken<List<? extends N1>>() {}, new TypeToken<List<? extends N1>>() {});
    assertAssignable(new TypeToken<List<? super N1>>() {}, new TypeToken<List<? super N1>>() {});
    assertAssignable(
        new TypeToken<List<? extends Number>>() {}, new TypeToken<List<? extends Number>>() {});
    assertAssignable(
        new TypeToken<List<? super Number>>() {}, new TypeToken<List<? super Number>>() {});
  }

    @Volatile var callsPerHost = AtomicInteger(0)
      private set

    fun reuseCallsPerHostFrom(other: AsyncCall) {
      this.callsPerHost = other.callsPerHost
    }

    val host: String
      get() = originalRequest.url.host

    val request: Request
      get() = originalRequest

    val call: RealCall
      get() = this@RealCall

    /**

  private final transient int[] axesSizeProduct;

  static <E> List<List<E>> create(List<? extends List<? extends E>> lists) {
    ImmutableList.Builder<List<E>> axesBuilder = new ImmutableList.Builder<>(lists.size());
    for (List<? extends E> list : lists) {
      List<E> copy = ImmutableList.copyOf(list);
      if (copy.isEmpty()) {
        return ImmutableList.of();
      }
      axesBuilder.add(copy);
    }

  // For example:
  // class Holder<T> {
  //   void set(T data) {...}
  // }
  // Holder<List<?>> should *not* resolve the set() method to set(List<?> data).
  // Instead, it should create a capture of the wildcard so that set() rejects any List<T>.
  private static class WildcardCapturer {

    static final WildcardCapturer INSTANCE = new WildcardCapturer();

              protected List<String> create(String[] elements) {
                // For this test we trust ArrayList works
                List<String> list = new ArrayList<>();
                Collections.addAll(list, elements);
                return new AbstractSequentialList<String>() {
                  @Override
                  public int size() {
                    return list.size();
                  }

        assertTrue(true);
    }

    public void test_setCommandList_empty() throws Exception {
        final List<String> commands = new ArrayList<>();
        generator.setCommandList(commands);
        assertTrue(true);
    }

    public void test_setCommandList_multiple() throws Exception {
        final List<String> commands = Arrays.asList("command1", "command2", "command3");
        generator.setCommandList(commands);