import java.time.Duration;
import java.util.concurrent.TimeUnit;

/**
 * An object that accurately measures <i>elapsed time</i>: the measured duration between two
 * successive readings of "now" in the same process.
 *
 * <p>In contrast, <i>wall time</i> is a reading of "now" as given by a method like
 * {@link System#currentTimeMillis()}, best represented as an {@link java.time.Instant}. Such values

   * for an RPC may wait for a similar call that requests a long timeout, or a call by an
   * unprivileged user may return a resource accessible only to a privileged user making a similar
   * call. To prevent this problem, create a key object that includes all values that affect the
   * result of the query. Or use {@code LoadingCache.get(K)}, which lacks the ability to refer to
   * state other than that in the key.
   *

</source>

<!--
    We used to set this only for packages that had manual supersource. That
    worked everywhere that I know of except for one place: when running the GWT
    util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see https://goo.gl/pRV3Yn for details.

    The summary is that it ignores one file in favor of the other.

</source>

<!--
    We used to set this only for packages that had manual supersource. That
    worked everywhere that I know of except for one place: when running the GWT
    util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see https://goo.gl/pRV3Yn for details.

    The summary is that it ignores one file in favor of the other.

   * nullness analysis might not understand that the field has been populated. To avoid that problem
   * without having to add {@code @SuppressWarnings}, the code can call this method.
   *
   * <p>Why <i>not</i> just add {@code SuppressWarnings}? The problem is that this method is
   * typically useful for {@code return} statements. That leaves the code with two options: Either

 *
 * <p>For {@code ImmutableMultiset} in particular, I ran into a problem with the {@code
 * GwtSerializationDependencies} approach: When autogenerating a serializer for the new class, GWT
 * tries to refer to our dummy serializer for the superclass,
 * ImmutableMultiset_CustomFieldSerializer. But that type has no methods (since it's never actually
 * used). We could probably fix the problem by adding dummy methods to that class, but that is

   * call cancel() and be unable to cancel the delegate.
   * There are a number of ways to solve this, none of which are very pretty, and it is currently
   * believed to be a purely theoretical problem (since the other actions should supply sufficient
   * write-barriers).
   */

  @CheckForNull @LazyInit private ListenableFuture<V> delegateRef;
  @CheckForNull @LazyInit private ScheduledFuture<?> timer;

    `@Deprecated` APIs will remain (again, unless they are `@Beta`). We have no
    plans to start removing things again, but officially, we're leaving our
    options open in case of surprises (like, say, a serious security problem).

3.  Guava has one dependency that is needed for linkage at runtime:
    `com.google.guava:failureaccess:1.0.2`. It also has
    [some annotation-only dependencies][guava-deps], which we discuss in more

</source>

<!--
    We used to set this only for packages that had manual supersource. That
    worked everywhere that I know of except for one place: when running the GWT
    util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see https://goo.gl/pRV3Yn for details.

    The summary is that it ignores one file in favor of the other.

</source>

<!--
    We used to set this only for packages that had manual supersource. That
    worked everywhere that I know of except for one place: when running the GWT
    util.concurrent tests under Guava.

    The problem is that GWT responds poorly to two .gwt.xml files in the same
    Java package; see https://goo.gl/pRV3Yn for details.

    The summary is that it ignores one file in favor of the other.