*       <i>compile</i> against Android. Now, this might be an artifact of our build system, one
 *       that we could probably work around. Or we could manually strip the test from open-source
 *       Guava while continuing to run it internally, as we do with many other tests. This would
 *       suffice because we our Android users and tests are using the open-source version, which

     * filesystem) does our prod code look up the username. Thus, this test doesn't necessarily test
     * anything interesting under most environments. Still, we can run it (except for Android, at
     * least old versions), so we mostly do. This is useful because we don't actually run our CI on
     * Windows under Java 8, at least as of this writing.
     *

   * to custom TypeVariable implementations. As a result, we need to make sure our TypeVariable
   * implementation respects symmetry. Moreover, we don't want to reconstruct a native type variable
   * {@code <A>} using our implementation unless some of its bounds have changed in resolution. This

 *       <i>compile</i> against Android. Now, this might be an artifact of our build system, one
 *       that we could probably work around. Or we could manually strip the test from open-source
 *       Guava while continuing to run it internally, as we do with many other tests. This would
 *       suffice because we our Android users and tests are using the open-source version, which

     *   <li>If this field's value is some other thread object, we know that it's not our thread.
     *   <li>If this field's value == null because it originally belonged to another thread and that
     *       thread cleared it, we still know that it's not associated with our thread
     *   <li>If this field's value == null because it was associated with our thread and was
     *       cleared, we know that we're not executing inline any more

        Be aware, though: most feature requests are not accepted, even if they're suggested by
        a full-time Guava team member. [Feedback](https://stackoverflow.com/a/4543114) from our
        users indicates that they really appreciate Guava's high power-to-weight ratio. It's
        important to us to keep Guava as easy to use and understand as we can. That means boiling

     * filesystem) does our prod code look up the username. Thus, this test doesn't necessarily test
     * anything interesting under most environments. Still, we can run it (except for Android, at
     * least old versions), so we mostly do. This is useful because we don't actually run our CI on
     * Windows under Java 8, at least as of this writing.
     *

flavor.

-   Snapshot API Docs: [guava][guava-snapshot-api-docs]
-   Snapshot API Diffs: [guava][guava-snapshot-api-diffs]

## Learn about Guava

-   Our users' guide, [Guava Explained]
-   [A nice collection](https://www.tfnico.com/presentations/google-guava) of
    other helpful links

## Links

-   [GitHub project](https://github.com/google/guava)

   *     by subsequent {@code get()} calls
   * @throws IllegalArgumentException if {@code duration} is not positive
   * @since 33.1.0
   */
  @Beta // only until we're confident that Java 8+ APIs are safe for our Android users
  @J2ktIncompatible
  @GwtIncompatible // java.time.Duration
  @SuppressWarnings("Java7ApiChecker") // no more dangerous that wherever the user got the Duration
  @IgnoreJRERequirement

public final class EnumBiMap<K extends Enum<K>, V extends Enum<V>> extends AbstractBiMap<K, V> {
  /*
   * J2CL's EnumMap does not need the Class instance, so we can use Object.class instead. (Or we
   * could use null, but that messes with our nullness checking, including under J2KT. We could
   * probably work around it by changing how we annotate the J2CL EnumMap, but that's probably more
   * trouble than just using Object.class.)
   *