protected <K, V> Map<K, V> create() {
    TestMap<K, V> inner = new TestMap<>(new HashMap<K, V>(), mutex);
    Map<K, V> outer = Synchronized.map(inner, mutex);
    return outer;
  }

  static class TestMap<K, V> extends ForwardingMap<K, V> implements Serializable {
    public final Object mutex;
    private final Map<K, V> delegate;

    public TestMap(Map<K, V> delegate, Object mutex) {
      checkNotNull(mutex);

  }

  public void test_useForNull_twice() {
    Joiner j = Joiner.on("x").useForNull("y");
    assertThrows(UnsupportedOperationException.class, () -> j.useForNull("y"));
  }

  public void testMap() {
    MapJoiner j = Joiner.on(';').withKeyValueSeparator(':');
    assertEquals("", j.join(ImmutableMap.of()));
    assertEquals(":", j.join(ImmutableMap.of("", "")));

    String i18nHash = "7fa826962ce2079c8334cd4ebf33aea4";
    assertEquals(i18nHash, Files.hash(i18nFile, Hashing.md5()).toString());
  }

  public void testMap() throws IOException {
    // Test data
    int size = 1024;
    byte[] bytes = newPreFilledByteArray(size);

    // Setup
    File file = createTempFile();
    Files.write(bytes, file);

    // Test

    String i18nHash = "7fa826962ce2079c8334cd4ebf33aea4";
    assertEquals(i18nHash, Files.hash(i18nFile, Hashing.md5()).toString());
  }

  public void testMap() throws IOException {
    // Test data
    int size = 1024;
    byte[] bytes = newPreFilledByteArray(size);

    // Setup
    File file = createTempFile();
    Files.write(bytes, file);

    // Test

	const step = 13
	if r >= 'a' && r <= 'z' {
		return ((r - 'a' + step) % 26) + 'a'
	}
	if r >= 'A' && r <= 'Z' {
		return ((r - 'A' + step) % 26) + 'A'
	}
	return r
}

func TestMap(t *testing.T) {
	// Run a couple of awful growth/shrinkage tests
	a := tenRunes('a')

	// 1.  Grow. This triggers two reallocations in Map.
	maxRune := func(r rune) rune { return unicode.MaxRune }

 *
 * <pre>
 * copyBeanToMap(srcBean, destMap);
 * copyMapToBean(srcMap, destBean);
 * </pre>
 * <p>
 * You can also create a new instance of the destination JavaBean or {@link Map} and copy to it.
 * </p>
 *
 * <pre>
 * DestBean destBean = copyBeanToNewBean(srcBean, DestBean.class);
 * DestBean destBean = copyMapToNewBean(srcMap, DestBean.class);
 * Map&lt;String, Object&gt; destMap = copyBeanToNewMap(srcBean);
 * </pre>
 * <p>