import org.jspecify.annotations.Nullable;

/**
 * A {@link ListenableFuture} which forwards all its method calls to another future. Subclasses
 * should override one or more methods to modify the behavior of the backing future as desired per
 * the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p>Most subclasses can just use {@link SimpleForwardingListenableFuture}.
 *
 * @author Shardul Deo

import org.jspecify.annotations.Nullable;

/**
 * {@link Error} variant of {@link java.util.concurrent.ExecutionException}. As with {@code
 * ExecutionException}, the error's {@linkplain #getCause() cause} comes from a failed task,
 * possibly run in another thread. That cause should itself be an {@code Error}; if not, use {@code
 * ExecutionException} or {@link UncheckedExecutionException}. This allows the client code to

 * multiple sub-contexts using different credentials (if necessary).
 *
 * {@link #withDefaultCredentials()}, {@link #withAnonymousCredentials()}, {@link #withCredentials(Credentials)}
 * allow to create such sub-contexts.
 *
 *
 * Implementors of this interface should extend {@link jcifs.context.BaseContext} or
 * {@link jcifs.context.CIFSContextWrapper} to get forward compatibility.
 *
 * @author mbechler
 *
 */

## Ejemplo

Para un ejemplo simple, consideremos una estructura de archivos similar a la descrita en [Aplicaciones Más Grandes](../tutorial/bigger-applications.md){.internal-link target=_blank} y [Testing](../tutorial/testing.md){.internal-link target=_blank}:

```
.
├── app

   * State#RUNNING}. Services that need to cancel startup work can override {@link #doCancelStart}.
   */
  @ForOverride
  protected abstract void doStop();

  /**
   * This method is called by {@link #stopAsync} when the service is still starting (i.e. {@link
   * #startAsync} has been called but {@link #notifyStarted} has not). Subclasses can override the

  /**
   * Returns the empty iterator.
   *
   * <p>The {@link Iterable} equivalent of this method is {@link ImmutableSet#of()}.
   */
  static <T extends @Nullable Object> UnmodifiableIterator<T> emptyIterator() {
    return emptyListIterator();
  }

  /**
   * Returns the empty iterator.
   *
   * <p>The {@link Iterable} equivalent of this method is {@link ImmutableSet#of()}.
   */

    reverse(array, fromIndex, toIndex);
  }

  /**
   * Returns a fixed-size list backed by the specified array, similar to {@link
   * Arrays#asList(Object[])}. The list supports {@link List#set(int, Object)}, but any attempt to
   * set a value to {@code null} will result in a {@link NullPointerException}.
   *
   * <p>The returned list maintains the values, but not the identities, of {@code Character} objects

    }
    return handleInvocation(proxy, method, args);
  }

  /**
   * {@link #invoke} delegates to this method upon any method invocation on the proxy instance,
   * except {@link Object#equals}, {@link Object#hashCode} and {@link Object#toString}. The result
   * will be returned as the proxied method's return value.
   *
   * <p>Unlike {@link #invoke}, {@code args} will never be null. When the method has no parameter,

   * Support for {@link ListIterator#set(Object)}; ignored for plain {@link Iterator}
   * implementations.
   */
  SUPPORTS_SET;

  /**
   * A set containing none of the optional features of the {@link Iterator} or {@link ListIterator}
   * interfaces.
   */
  public static final Set<IteratorFeature> UNMODIFIABLE = emptySet();

  /**
   * A set containing all of the optional features of the {@link Iterator} and {@link ListIterator}

 * <p>There are deviations from this if there are failures or if {@link Service#stopAsync} is called
 * before the {@link Service} reaches the {@linkplain State#RUNNING RUNNING} state. The set of legal
 * transitions form a <a href="http://en.wikipedia.org/wiki/Directed_acyclic_graph">DAG</a>,
 * therefore every method of the listener will be called at most once. N.B. The {@link State#FAILED}