}
            })
        .start();

    // wait for the computingEntry to be created
    computationStarted.await();
    cache.invalidateAll();
    // let the computation proceed
    computingLatch.countDown();
    // don't check cache.size() until we know the get("b") call is complete
    computationComplete.await();

              }
            })
        .start();

    // wait for the computingEntry to be created
    computationStarted.await();
    cache.invalidateAll();
    // let the computation proceed
    computingLatch.countDown();
    // don't check cache.size() until we know the get("b") call is complete
    computationComplete.await();

import java.util.SortedSet;
import org.jspecify.annotations.NullMarked;

/**
 * Generators of different types of sets and derived collections from sets.
 *
 * @author Kevin Bourrillion
 * @author Jared Levy
 * @author Hayward Chan
 */
@GwtCompatible
@NullMarked
public class SetGenerators {

  public static class ImmutableSetCopyOfGenerator extends TestStringSetGenerator {
    @Override

import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.jspecify.annotations.NullMarked;

/**
 * Tests for {@code EnumBiMap}.
 *
 * @author Mike Bostock
 * @author Jared Levy
 */
@J2ktIncompatible // EnumBimap
@GwtCompatible
@NullMarked
public class EnumBiMapTest extends TestCase {
  private enum Currency {
    DOLLAR,
    FRANC,
    PESO,
    POUND,
    YEN
  }

        // We will return a composite buffer from the test when building the full packet.
        // To keep this helper simple, return base and let the caller append/pad and inject ctx.
        return base;
    }

    /**
     * Build a full SMB2 packet combining header and provided body, optionally injecting context bytes.
     */

So, what we will do next is add the code to document how that *external API* should look like to receive the callback from *your API*.

That documentation will show up in the Swagger UI at `/docs` in your API, and it will let external developers know how to build the *external API*.

This example doesn't implement the callback itself (that could be just a line of code), only the documentation part.

/// tip

 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table">{@code Table}</a>.
 *
 * @author Jared Levy
 * @author Louis Wasserman
 * @since 7.0
 */
@GwtCompatible
public class TreeBasedTable<R, C, V> extends StandardRowSortedTable<R, C, V> {
  private final Comparator<? super C> columnComparator;

import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.jspecify.annotations.NullMarked;

/**
 * Tests for {@code EnumBiMap}.
 *
 * @author Mike Bostock
 * @author Jared Levy
 */
@J2ktIncompatible // EnumBimap
@GwtCompatible
@NullMarked
public class EnumBiMapTest extends TestCase {
  private enum Currency {
    DOLLAR,
    FRANC,
    PESO,
    POUND,
    YEN
  }

import org.jspecify.annotations.Nullable;

/**
 * Tests for {@link Maps#transformValues} when the backing map's views have iterators that don't
 * support {@code remove()}.
 *
 * @author Jared Levy
 */
@GwtCompatible
@NullMarked
public class MapsTransformValuesUnmodifiableIteratorTest extends MapInterfaceTest<String, String> {
  // TODO(jlevy): Move shared code of this class and MapsTransformValuesTest

 * <p>The {@code standard} methods and the collection views they return are not guaranteed to be
 * thread-safe, even when all of the methods that they depend on are thread-safe.
 *
 * @author Kevin Bourrillion
 * @author Jared Levy
 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible
public abstract class ForwardingMap<K extends @Nullable Object, V extends @Nullable Object>
    extends ForwardingObject implements Map<K, V> {