if (ATOMIC_HELPER.casValue(this, null, valueToSet)) {
        // the listener is responsible for calling completeWithFuture, directExecutor is appropriate
        // since all we are doing is unpacking a completed future which should be fast.
        try {
          future.addListener(valueToSet, DirectExecutor.INSTANCE);
        } catch (Throwable t) {

 *
 * <h3>Non-preconditions</h3>
 *
 * <p>It is of course possible to use the methods of this class to check for invalid conditions
 * which are <i>not the caller's fault</i>. Doing so is <b>not recommended</b> because it is
 * misleading to future readers of the code and of stack traces. See <a
 * href="https://github.com/google/guava/wiki/ConditionalFailuresExplained">Conditional failures

  @LazyInit @CheckForNull private transient TypeResolver covariantTypeResolver;

  /**
   * Constructs a new type token of {@code T}.
   *
   * <p>Clients create an empty anonymous subclass. Doing so embeds the type parameter in the
   * anonymous class's type hierarchy so we can reconstitute it at runtime despite erasure.
   *
   * <p>For example:
   *
   * <pre>{@code

 *
 * <h3>Non-preconditions</h3>
 *
 * <p>It is of course possible to use the methods of this class to check for invalid conditions
 * which are <i>not the caller's fault</i>. Doing so is <b>not recommended</b> because it is
 * misleading to future readers of the code and of stack traces. See <a
 * href="https://github.com/google/guava/wiki/ConditionalFailuresExplained">Conditional failures

      case 1:
        return is(sequence.charAt(0));
      case 2:
        return isEither(sequence.charAt(0), sequence.charAt(1));
      default:
        // TODO(lowasser): is it potentially worth just going ahead and building a precomputed
        // matcher?
        return new AnyOf(sequence);
    }
  }

  /**
   * Returns a {@code char} matcher that matches any BMP character not present in the given

      case 1:
        return is(sequence.charAt(0));
      case 2:
        return isEither(sequence.charAt(0), sequence.charAt(1));
      default:
        // TODO(lowasser): is it potentially worth just going ahead and building a precomputed
        // matcher?
        return new AnyOf(sequence);
    }
  }

  /**
   * Returns a {@code char} matcher that matches any BMP character not present in the given