* otherwise returns an empty stream.
   */
  public static <T> Stream<T> stream(com.google.common.base.Optional<T> optional) {
    return optional.isPresent() ? Stream.of(optional.get()) : Stream.empty();
  }

  /**
   * If a value is present in {@code optional}, returns a stream containing only that element,
   * otherwise returns an empty stream.
   *

# This file contains only comments and whitespace

@AfterClass
public static void afterClass() {
    runner.close();
    runner.clean();
}
```

### Testing Best Practices

- Minimize `Thread.sleep()` - use only when absolutely necessary
- For timestamp tests: use minimal delays (50-100ms)
- Clean only test-specific indices (not `_all` unless needed)
- Use `runner.refresh()` after index operations
- Test with realistic multilingual content

### Key Test Classes

   *
   * @param url a URL with only the scheme, hostname, and port specified.
   */
  open fun proxySelectStart(
    call: Call,
    url: HttpUrl,
  ) {
  }

  /**
   * Invoked after proxy selection.
   *
   * Note that the list of proxies is never null, but it may be a list containing
   * only [Proxy.NO_PROXY]. This comes up in several situations:
   *

        assertNotNull(deleteResponse);
        assertFalse(deleteResponse.hasError());

        suggester.refresh();

        // Document-only should be deleted, Query-only should remain, Both should remain but as Query only
        assertEquals(2, suggester.getAllWordsNum());
        assertEquals(0, suggester.getDocumentWordsNum());
        assertEquals(2, suggester.getQueryWordsNum());
    }

    for (Type bound : bounds) {
      Type componentType = getComponentType(bound);
      if (componentType != null) {
        // Only the first bound can be a class or array.
        // Bounds after the first can only be interfaces.
        if (componentType instanceof Class) {
          Class<?> componentClass = (Class<?>) componentType;
          if (componentClass.isPrimitive()) {

     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getFrameworkDebug();

    /**
     * Is the property for the key 'framework.debug' true? <br>
     * The value is, e.g. false <br>
     * comment: Does it enable the Framework internal debug? (true only when emergency)

  @J2ktIncompatible
  @GwtIncompatible // used only from suite
  @AndroidIncompatible
  public static final class ImmutableLongArrayAsListGenerator extends TestLongListGenerator {
    @Override
    protected List<Long> create(Long[] elements) {
      return makeArray(elements).asList();
    }
  }

  @J2ktIncompatible
  @GwtIncompatible // used only from suite
  @AndroidIncompatible

      // it is a name, all IPs for that name should be tried. If it is an IP address, only that IP
      // address should be tried.
      val address = address ?: return hostName

      // The InetSocketAddress has a specific address: we should only try that address. Therefore we
      // return the address and ignore any host name that may be available.
      return address.hostAddress

        ImmutableMap.of(
            3, ValueDifferenceImpl.create("c", "f"), 5, ValueDifferenceImpl.create("e", "g")),
        diff1.entriesDiffering());
    assertEquals(
        "not equal: only on left={2=b, 4=d}: only on right={6=z}: "
            + "value differences={3=(c, f), 5=(e, g)}",
        diff1.toString());

    MapDifference<Integer, String> diff2 = Maps.difference(right, left);
    assertFalse(diff2.areEqual());