assertEquals("", emptyUnicodeStringFalse.toString(), "toString should return empty string for empty input without zterm");

        // Test toString with a manually constructed UnicodeString (simulating rpc.unicode_string input)
        rpc.unicode_string dummyRus = new rpc.unicode_string();
        dummyRus.buffer = new short[] { 'T', 'e', 's', 't', 'i', 'n', 'g' };
        dummyRus.length = 14; // 7 characters * 2 bytes/char

@GwtCompatible
abstract class CollectionFuture<V extends @Nullable Object, C extends @Nullable Object>
    extends AggregateFuture<V, C> {
  /*
   * We access this field racily but safely. For discussion of a similar situation, see the comments
   * on the fields of TimeoutFuture. This field is slightly different from the fields discussed
   * there: cancel() never reads this field, only writes to it. That makes the race here completely

import java.util.Iterator;
import java.util.List;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.stream.Collector;
import org.jspecify.annotations.Nullable;

/**
 * GWT emulation of {@link com.google.common.collect.ImmutableSortedSet}.
 *
 * @author Hayward Chan
 */
public abstract class ImmutableSortedSet<E> extends ForwardingImmutableSet<E>
    implements SortedSet<E>, SortedIterable<E> {

     * Disabled by default - enable with -Dwitness.integration.test=true
     */
    @Test
    void testWitnessEnvironmentConfiguration() throws Exception {
        // Test simulating real witness environment scenarios
        // This test validates integration patterns without requiring real cluster

        // Simulate witness service discovery

    // below the values of characters in surrogate pairs, this cannot occur.
    // This approach does mean that we break out of the fast path code in cases
    // where we don't strictly need to, but this situation will almost never
    // occur in practice.
    if (safeMin >= Character.MIN_HIGH_SURROGATE) {
      // The safe range is empty or the all safe code points lie in or above the

Let's start with an example and then see it in detail.

We create an async function `lifespan()` with `yield` like this:

{* ../../docs_src/events/tutorial003.py hl[16,19] *}

import java.util.Comparator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.function.Function;
import java.util.stream.Collector;
import org.jspecify.annotations.Nullable;

/**
 * GWT emulation of {@link com.google.common.collect.ImmutableBiMap}.
 *
 * @author Hayward Chan
 */
public abstract class ImmutableBiMap<K, V> extends ForwardingImmutableMap<K, V>
    implements BiMap<K, V> {

It is just a standard function that can receive parameters.

It can be an `async def` or normal `def` function, **FastAPI** will know how to handle it correctly.

In this case, the task function will write to a file (simulating sending an email).

And as the write operation doesn't use `async` and `await`, we define the function with normal `def`:

{* ../../docs_src/background_tasks/tutorial001.py hl[6:9] *}

import jsinterop.annotations.JsMethod;
import jsinterop.annotations.JsPackage;
import jsinterop.annotations.JsProperty;
import jsinterop.annotations.JsType;
import org.jspecify.annotations.Nullable;

/**
 * Minimal GWT emulation of {@code com.google.common.collect.Platform}.
 *
 * @author Hayward Chan
 */
final class Platform {
  static <K extends @Nullable Object, V extends @Nullable Object>

  /** JavaLangAccess class name to load using reflection */
  @J2ktIncompatible @GwtIncompatible // not used by GWT emulation
  private static final String JAVA_LANG_ACCESS_CLASSNAME = "sun.misc.JavaLangAccess";

  /** SharedSecrets class name to load using reflection */
  @J2ktIncompatible
  @GwtIncompatible // not used by GWT emulation
  @VisibleForTesting
  static final String SHARED_SECRETS_CLASSNAME = "sun.misc.SharedSecrets";