*
     * <p>It is strongly encouraged to use {@link #add(String, Object)} instead and give value a
     * readable name.
     */
    @CanIgnoreReturnValue
    public ToStringHelper addValue(@Nullable Object value) {
      return addHolder(value);
    }

    /**
     * Adds an unnamed value to the formatted output.
     *

     *
     * <p>It is strongly encouraged to use {@link #add(String, Object)} instead and give value a
     * readable name.
     */
    @CanIgnoreReturnValue
    public ToStringHelper addValue(@Nullable Object value) {
      return addHolder(value);
    }

    /**
     * Adds an unnamed value to the formatted output.
     *

 * i.e. {@code if (key1.equals(key2))} then {@code striped.get(key1) == striped.get(key2)} (assuming
 * {@link Object#hashCode()} is correctly implemented for the keys). Note that if {@code key1} is
 * <strong>not</strong> equal to {@code key2}, it is <strong>not</strong> guaranteed that {@code
 * striped.get(key1) != striped.get(key2)}; the elements might nevertheless be mapped to the same

   * the backport does. For now, we're keeping the class declaration in *both* flavors so that both
   * flavors can read old data or data from the other flavor. However, we strongly discourage
   * relying on this, as we have made incompatible changes to serialized forms in the past and
   * expect to do so again, as discussed in https://github.com/google/guava#important-warnings.
   */

removed, at any time. If your code is a library itself (i.e. it is
used on the CLASSPATH of users outside your own control), you should
not use beta APIs, unless you [repackage] them. **If your
code is a library, we strongly recommend using the [Guava Beta Checker] to
ensure that you do not use any `@Beta` APIs!**

[Guava Beta Checker]: https://github.com/google/guava-beta-checker

<!-- References -->

import java.util.concurrent.atomic.AtomicBoolean;
import org.jspecify.annotations.Nullable;

/**
 * Utilities necessary for working with libraries that supply plain {@link Future} instances. Note
 * that, whenever possible, it is strongly preferred to modify those libraries to return {@code
 * ListenableFuture} directly.
 *
 * <p>For interoperability between {@code ListenableFuture} and <b>{@code CompletableFuture}</b>,

    time. If your code is a library itself (i.e., it is used on the CLASSPATH of
    users outside your own control), you should not use beta APIs unless you
    [repackage] them. **If your code is a library, we strongly recommend using
    the [Guava Beta Checker] to ensure that you do not use any `@Beta` APIs!**

2.  APIs without `@Beta` will remain binary-compatible for the indefinite

 *
 * <p>The {@link MapIteratorCache} assumes ownership of the backing map, and cannot guarantee
 * correctness in the face of external mutations to the backing map. As such, it is <b>strongly</b>
 * recommended that the caller does not persist a reference to the backing map (unless the backing
 * map is immutable).
 *
 * <p>This class is tailored toward use cases in common.graph. It is *NOT* a general purpose map.

 *
 * <p>The two primary implementations of this interface are {@link CharEscaper} and {@link
 * UnicodeEscaper}. They are heavily optimized for performance and greatly simplify the task of
 * implementing new escapers. It is strongly recommended that when implementing a new escaper you
 * extend one of these classes. If you find that you are unable to achieve the desired behavior
 * using either of these classes, please contact the Java libraries team for advice.

 * and {@link State#TERMINATED} states are terminal states, once a service enters either of these
 * states it cannot ever leave them.
 *
 * <p>Implementors of this interface are strongly encouraged to extend one of the abstract classes
 * in this package which implement this interface and make the threading and state management
 * easier.
 *
 * @author Jesse Wilson
 * @author Luke Sandberg