public String toString() {
      synchronized (mutex) {
        return delegate.toString();
      }
    }

    // Serialization invokes writeObject only when it's private.
    // The SynchronizedObject subclasses don't need a writeObject method since
    // they don't contain any non-transient member variables, while the
    // following writeObject() handles the SynchronizedObject members.

    @GwtIncompatible

    public String toString() {
      synchronized (mutex) {
        return delegate.toString();
      }
    }

    // Serialization invokes writeObject only when it's private.
    // The SynchronizedObject subclasses don't need a writeObject method since
    // they don't contain any non-transient member variables, while the
    // following writeObject() handles the SynchronizedObject members.

    @GwtIncompatible

   * {@link #copyInto} and forget the {@code SetView} itself.
   *
   * @since 2.0
   */
  public abstract static class SetView<E extends @Nullable Object> extends AbstractSet<E> {
    private SetView() {} // no subclasses but our own

    /**
     * Returns an immutable copy of the current contents of this set view. Does not support null
     * elements.
     *

_2019-02-05_

 *  Fix: Don't crash when using a custom `X509TrustManager` or `SSLSocket` on Android. When we
    removed obsolete code for Android 4.4 we inadvertently also removed support for custom
    subclasses. We've restored that support!


## Version 3.13.0

_2019-02-04_

 *  **This release bumps our minimum requirements to Java 8+ or Android 5+.** Cutting off old

En realidad, `Query`, `Path` y otros que verás a continuación crean objetos de subclases de una clase común `Param`, que es a su vez una subclase de la clase `FieldInfo` de Pydantic.

Y `Field` de Pydantic también regresa una instance de `FieldInfo`.

`Body` también devuelve objetos de una subclase de `FieldInfo` directamente. Y hay otros que verás más adelante que son subclases de la clase `Body`.

Y las herramientas también estarán felices porque tanto `RedirectResponse` como `JSONResponse` son subclases de `Response`, por lo que la anotación del tipo es correcta.

### Anotar una Subclase de Response { #annotate-a-response-subclass }

También puedes usar una subclase de `Response` en la anotación del tipo:

  }

  /**
   * Must be called at the end of each subclass's constructor. This method performs the "real"
   * initialization; we can't put this in the constructor because, in the case where futures are
   * already complete, we would not initialize the subclass before calling {@link
   * #collectValueFromNonCancelledFuture}. As this is called after the subclass is constructed,

import com.google.common.eventbus.Subscribe;
import com.google.common.eventbus.outside.AbstractNotAnnotatedInSuperclassTest.SubClass;
import java.util.ArrayList;
import java.util.List;

public class AbstractNotAnnotatedInSuperclassTest extends AbstractEventBusTest<SubClass> {
  abstract static class SuperClass {
    public abstract void overriddenInSubclassNowhereAnnotated(Object o);

Pode ser útil para retornar cabeçalhos e cookies personalizados, por exemplo.

## Retornando uma `Response` { #return-a-response }

Na verdade, você pode retornar qualquer `Response` ou subclasse dela.

/// tip | Dica

A própria `JSONResponse` é uma subclasse de `Response`.

///

E quando você retorna uma `Response`, o **FastAPI** vai repassá-la diretamente.

import com.google.common.eventbus.Subscribe;
import com.google.common.eventbus.outside.AbstractNotAnnotatedInSuperclassTest.SubClass;
import java.util.ArrayList;
import java.util.List;

public class AbstractNotAnnotatedInSuperclassTest extends AbstractEventBusTest<SubClass> {
  abstract static class SuperClass {
    public abstract void overriddenInSubclassNowhereAnnotated(Object o);