*/
@DoNotMock("Use Optional.of(value) or Optional.absent()")
@GwtCompatible(serializable = true)
@ElementTypesAreNonnullByDefault
public abstract class Optional<T> implements Serializable {
  /**
   * Returns an {@code Optional} instance with no contained reference.
   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> this method is equivalent to Java 8's
   * {@code Optional.empty}.
   */
  public static <T> Optional<T> absent() {

    List<Optional<Object>> optionals = ImmutableList.of(Optional.absent(), Optional.absent());
    assertThat(Optional.presentInstances(optionals)).isEmpty();
  }

  public void testPresentInstances_somePresent() {
    List<Optional<String>> optionals =
        ImmutableList.of(Optional.of("a"), Optional.<String>absent(), Optional.of("c"));

  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.Time lastTransitionTime = 3;

  // The reason for the condition's last transition.
  // +optional
  optional string reason = 4;

  // A human readable message indicating details about the transition.
  // +optional
  optional string message = 5;
}

// DaemonSetList is a collection of daemon sets.
message DaemonSetList {

  // +optional
  optional string version = 4;

  // Resource is one of the existing resource types.  "*" means all.
  // +optional
  optional string resource = 5;

  // Subresource is one of the existing resource types.  "" means none.
  // +optional
  optional string subresource = 6;

  // Name is the name of the resource being requested for a "get" or deleted for a "delete". "" (empty) means all.
  // +optional

  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.Time lastTransitionTime = 3;

  // The reason for the condition's last transition.
  // +optional
  optional string reason = 4;

  // A human readable message indicating details about the transition.
  // +optional
  optional string message = 5;
}

// DaemonSetList is a collection of daemon sets.
message DaemonSetList {
  // Standard list metadata.

  // +optional
  optional string reason = 4;

  // message is a human-readable explanation containing details about
  // the transition
  // +optional
  optional string message = 5;
}

// HorizontalPodAutoscalerList is a list of horizontal pod autoscaler objects.
message HorizontalPodAutoscalerList {
  // metadata is the standard list metadata.
  // +optional

  // one status to another
  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.Time lastTransitionTime = 3;

  // reason is the reason for the condition's last transition.
  // +optional
  optional string reason = 4;

  // message is a human-readable explanation containing details about
  // the transition
  // +optional
  optional string message = 5;
}

     *
     * @return an {@link Optional} containing the map of user properties, or empty if not set
     */
    @Nonnull
    Optional<Map<String, String>> userProperties();

    /**
     * Indicates whether to show the version information and exit.
     *
     * @return an {@link Optional} containing the boolean flag, or empty if not set
     */
    @Nonnull
    Optional<Boolean> showVersionAndExit();

    /**

  // handle values up to 64kB.
  // +optional
  optional string note = 10;

  // type is the type of this event (Normal, Warning), new types could be added in the future.
  // It is machine-readable.
  // +optional
  optional string type = 11;

  // deprecatedSource is the deprecated field assuring backward compatibility with core.v1 Event type.
  // +optional
  optional k8s.io.api.core.v1.EventSource deprecatedSource = 12;

  // +optional
  optional string reason = 3;

  // Message regarding the last termination of the container
  // +optional
  optional string message = 4;

  // Time at which previous execution of the container started
  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.Time startedAt = 5;

  // Time at which the container last terminated
  // +optional