/** Constructor for use by subclasses. */
  protected Converter() {
    this(true);
  }

  /** Constructor used only by {@code LegacyConverter} to suspend automatic null-handling. */
  Converter(boolean handleNullAutomatically) {
    this.handleNullAutomatically = handleNullAutomatically;
  }

  // SPI methods (what subclasses must implement)

  /**

  @ParametricNullness
  V checkValue(@ParametricNullness V value) {
    return value;
  }

  /**
   * Specifies the delegate maps going in each direction. Called by the constructor and by
   * subclasses during deserialization.
   */
  void setDelegates(Map<K, V> forward, Map<V, K> backward) {
    checkState(delegate == null);
    checkState(inverse == null);
    checkArgument(forward.isEmpty());

     */
    Builder<K, V> makeBuilder(int size) {
      return new Builder<>(size);
    }

    private static final long serialVersionUID = 0;
  }

  /**
   * Returns a serializable form of this object. Non-public subclasses should not override this

    as a dependency. All other OAuth2 classes inherit from it and customize it for
    each OAuth2 flow.

    You normally would not create a new class inheriting from it but use one of the
    existing subclasses, and maybe compose them if you want to support multiple flows.

    Read more about it in the
    [FastAPI docs for Security](https://fastapi.tiangolo.com/tutorial/security/).
    """

    def __init__(

              <exclude>%regex[.*Tester.class]</exclude>
              <!-- Anonymous TestCase subclasses in GeneratedMonitorTest -->
              <exclude>%regex[.*[$]\d+.class]</exclude>
            </excludes>
            <redirectTestOutputToFile>true</redirectTestOutputToFile>
            <runOrder>alphabetical</runOrder>

              <exclude>%regex[.*Tester.class]</exclude>
              <!-- Anonymous TestCase subclasses in GeneratedMonitorTest -->
              <exclude>%regex[.*[$]\d+.class]</exclude>
            </excludes>
            <redirectTestOutputToFile>true</redirectTestOutputToFile>
            <runOrder>alphabetical</runOrder>

```

This simple case is handled automatically by FastAPI because the return type annotation is the class (or a subclass of) `Response`.

And tools will also be happy because both `RedirectResponse` and `JSONResponse` are subclasses of `Response`, so the type annotation is correct.

### Annotate a Response Subclass

You can also use a subclass of `Response` in the type annotation:

```Python hl_lines="8-9"

import java.util.Set;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Tests representing the contract of {@link Map}. Concrete subclasses of this base class test
 * conformance of concrete {@link Map} subclasses to that contract.
 *
 * @param <K> the type of keys used by the maps under test
 * @param <V> the type of mapped values used the maps under test
 * @author George van den Driessche
 */

  @Override
  public String toString() {
    return String.format(Locale.ROOT, "RateLimiter[stableRate=%3.1fqps]", getRate());
  }

  abstract static class SleepingStopwatch {
    /** Constructor for use by subclasses. */
    protected SleepingStopwatch() {}

    /*
     * We always hold the mutex when calling this. TODO(cpovirk): Is that important? Perhaps we need

       * Converter.apply has a non-nullable parameter type but doesn't throw for null arguments. For
       * more information, see the comments in that class.
       *
       * We already know that that's how it behaves, and subclasses of Converter can't change that
       * behavior. So there's no sense in making all subclass authors exclude the method from any
       * NullPointerTester tests that they have.
       */