* @return the first element, or null if the collection is empty
     * @since Java 21
     */
    public static <E> E getFirst(final SequencedCollection<E> collection) {
        return collection.isEmpty() ? null : collection.getFirst();
    }

    /**
     * Returns the last element of a sequenced collection.
     *
     * @param <E> the element type

  private static class Holder<T> {
    List<T>[] matrix;

    void setList(List<T> list) {}
  }

  public void testWildcardCaptured_methodParameter_upperBound() throws Exception {
    TypeToken<Holder<?>> type = new TypeToken<Holder<?>>() {};
    ImmutableList<Parameter> parameters =
        type.method(Holder.class.getDeclaredMethod("setList", List.class)).getParameters();
    assertThat(parameters).hasSize(1);

   * @since 12.0
   */
  @Override
  public @Nullable E ceiling(E e) {
    return Iterables.<@Nullable E>getFirst(tailSet(e, true), null);
  }

  /**
   * @since 12.0
   */
  @GwtIncompatible // NavigableSet
  @Override
  public @Nullable E higher(E e) {
    return Iterables.<@Nullable E>getFirst(tailSet(e, false), null);
  }

  @Override
  public E first() {
    return iterator().next();
  }

    public @Nullable E pollLast() {
      synchronized (mutex) {
        return delegate().pollLast();
      }
    }

    @Override
    public E getFirst() {
      synchronized (mutex) {
        return delegate().getFirst();
      }
    }

    @Override
    public E getLast() {
      synchronized (mutex) {
        return delegate().getLast();
      }
    }

    public @Nullable E pollLast() {
      synchronized (mutex) {
        return delegate().pollLast();
      }
    }

    @Override
    public E getFirst() {
      synchronized (mutex) {
        return delegate().getFirst();
      }
    }

    @Override
    public E getLast() {
      synchronized (mutex) {
        return delegate().getLast();
      }
    }

        }
    }

    @Override
    protected void writeHeaders(final HttpServletResponse response) {
        ComponentUtil.getFessConfig().getApiJsonResponseHeaderList().forEach(e -> response.setHeader(e.getFirst(), e.getSecond()));
    }

    /**
     * Writes a JSON response.
     * @param status The status code.
     * @param t The throwable.
     */

   *
   * @throws NullPointerException if the first element is null; if this is a possibility, use {@code
   *     iterator().next()} or {@link Iterables#getFirst} instead.
   */
  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
  public final Optional<@NonNull E> first() {
    Iterator<E> iterator = getDelegate().iterator();

   *
   * @throws NullPointerException if the first element is null; if this is a possibility, use {@code
   *     iterator().next()} or {@link Iterables#getFirst} instead.
   */
  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
  public final Optional<@NonNull E> first() {
    Iterator<E> iterator = getDelegate().iterator();

    }

    <T> void clearReferenceQueue(ReferenceQueue<T> referenceQueue) {
      while (referenceQueue.poll() != null) {}
    }

    /** Returns first entry of bin for given hash. */
    @Nullable E getFirst(int hash) {
      // read this volatile field only once
      AtomicReferenceArray<E> table = this.table;
      return table.get(hash & (table.length() - 1));
    }

        final Pair<String, String>[] designJspFileNames = systemHelper.getDesignJspFileNames();
        assertEquals(1, designJspFileNames.length);
        assertEquals("xxx", designJspFileNames[0].getFirst());
        assertEquals("yyy", designJspFileNames[0].getSecond());
    }

    @Test
    public void test_setForceStop() {
        assertFalse(systemHelper.isForceStop());