* controls the order in which events are dispatched, while the executor controls how (i.e. on which
 * thread) the subscriber is actually called when an event is dispatched to it.
 *
 * @author Colin Decker
 */
abstract class Dispatcher {

  /**
   * Returns a dispatcher that queues events that are posted reentrantly on a thread that is already

Then, we could use this `checker` in a `Depends(checker)`, instead of `Depends(FixedContentQueryChecker)`, because the dependency is the instance, `checker`, not the class itself.

And when solving the dependency, **FastAPI** will call this `checker` like:

```Python
checker(q="somequery")
```

* A PR should have a specific use case that it is solving.

* If the PR is for a feature, it should have docs.
    * Unless it's a feature we want to discourage, like support for a corner case that we don't want users to use.

import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.CopyOnWriteArraySet;
import org.jspecify.annotations.Nullable;

/**
 * Registry of subscribers to a single event bus.
 *
 * @author Colin Decker
 */
final class SubscriberRegistry {

  /**
   * All registered subscribers, indexed by event type.
   *
   * <p>The {@link CopyOnWriteArraySet} values make it easy and relatively lightweight to get an

You can define dependencies that in turn can define dependencies themselves.

In the end, a hierarchical tree of dependencies is built, and the **Dependency Injection** system takes care of solving all these dependencies for you (and their sub-dependencies) and providing (injecting) the results at each step.

For example, let's say you have 4 API endpoints (*path operations*):

* `/items/public/`

import java.util.Arrays;
import java.util.logging.Logger;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * {@link SourceSinkFactory} implementations.
 *
 * @author Colin Decker
 */
@NullUnmarked
public class SourceSinkFactories {

  private SourceSinkFactories() {}

  public static CharSourceFactory stringCharSourceFactory() {
    return new StringSourceFactory();
  }

 *
 * <p>See the Guava User Guide article on <a
 * href="https://github.com/google/guava/wiki/PrimitivesExplained#unsigned-support">unsigned
 * primitive utilities</a>.
 *
 * @author Louis Wasserman
 * @author Colin Evans
 * @since 11.0
 */
@GwtCompatible
public final class UnsignedLong extends Number implements Comparable<UnsignedLong> {

  private static final long UNSIGNED_MASK = 0x7fffffffffffffffL;

import java.util.stream.Stream;
import junit.framework.TestSuite;
import org.jspecify.annotations.NullUnmarked;

/**
 * Tests for the default implementations of {@code CharSource} methods.
 *
 * @author Colin Decker
 */
@NullUnmarked
public class CharSourceTest extends IoTestCase {

  @AndroidIncompatible // Android doesn't understand suites whose tests lack default constructors.
  public static TestSuite suite() {

import java.util.Objects;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests for {@link Closer}.
 *
 * @author Colin Decker
 */
@NullUnmarked
public class CloserTest extends TestCase {

  private TestSuppressor suppressor;

  @Override
  protected void setUp() throws Exception {
    suppressor = new TestSuppressor();
  }

import junit.framework.TestSuite;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests for the default implementations of {@code ByteSource} methods.
 *
 * @author Colin Decker
 */
@NullUnmarked
public class ByteSourceTest extends IoTestCase {

  @AndroidIncompatible // Android doesn't understand suites whose tests lack default constructors.
  public static TestSuite suite() {