MapMaker builder) {
    if (builder.getKeyStrength() == Strength.STRONG
        && builder.getValueStrength() == Strength.STRONG) {
      return new MapMakerInternalMap<>(builder, StrongKeyStrongValueEntry.Helper.<K, V>instance());
    }
    if (builder.getKeyStrength() == Strength.STRONG
        && builder.getValueStrength() == Strength.WEAK) {

   * @throws IllegalStateException if the key strength was already set
   */
  @GwtIncompatible // java.lang.ref.WeakReference
  @CanIgnoreReturnValue
  public CacheBuilder<K, V> weakKeys() {
    return setKeyStrength(Strength.WEAK);
  }

  @CanIgnoreReturnValue
  CacheBuilder<K, V> setKeyStrength(Strength strength) {
    checkState(keyStrength == null, "Key strength was already set to %s", keyStrength);

  }

  private fun Snapshot.assertValue(
    index: Int,
    value: String,
  ) {
    getSource(index).use { source ->
      assertThat(sourceAsString(source)).isEqualTo(value)
      assertThat(getLength(index)).isEqualTo(value.length.toLong())
    }
  }

  private fun sourceAsString(source: Source) = source.buffer().readUtf8()

  private fun Editor.assertInoperable() {