} else {
      return ~index;
    }
  }

  // Pretend the comparator can compare anything. If it turns out it can't
  // compare two elements, it'll throw a CCE. Only methods that are specified to
  // throw CCE should call this.
  @SuppressWarnings("unchecked")
  Comparator<Object> unsafeComparator() {
    return (Comparator<Object>) comparator;
  }

  private final String value;

  LegacyComparable(String value) {
    this.value = value;
  }

  @Override
  public int compareTo(Object object) {
    // This method is spec'd to throw CCE if object is of the wrong type
    LegacyComparable that = (LegacyComparable) object;
    return this.value.compareTo(that.value);
  }

  @Override
  public boolean equals(@Nullable Object object) {

    /** Constructor for use by subclasses. */
    public StandardKeySet() {
      super(ForwardingSortedMap.this);
    }
  }

  // unsafe, but worst case is a CCE or NPE is thrown, which callers will be expecting
  @SuppressWarnings({"unchecked", "nullness"})
  static int unsafeCompare(
      @Nullable Comparator<?> comparator, @Nullable Object o1, @Nullable Object o2) {

  }

  @Override
  public boolean contains(@Nullable Object object) {
    if (object == null) {
      return false;
    }
    try {
      @SuppressWarnings("unchecked") // The worst case is usually CCE, which we catch.
      C c = (C) object;
      return range.contains(c);
    } catch (ClassCastException e) {
      return false;
    }
  }

  @Override