* ListenableFuture} directly.
 *
 * <p>For interoperability between {@code ListenableFuture} and <b>{@code CompletableFuture}</b>,
 * consider <a href="https://github.com/lukas-krecan/future-converter">Future Converter</a>.
 *
 * @author Sven Mawson
 * @since 10.0 (replacing {@code Futures.makeListenable}, which existed in 1.0)
 */
@J2ktIncompatible
@GwtIncompatible
@ElementTypesAreNonnullByDefault

 *   <li>{@link Ascii}
 *   <li>{@link CaseFormat}
 *   <li>{@link CharMatcher}
 *   <li>{@link Splitter}
 *   <li>{@link Strings}
 * </ul>
 *
 * <h3>Function types</h3>
 *
 * <ul>
 *   <li>{@link Converter}
 *   <li>{@link Equivalence}
 * </ul>
 *
 * <h3>Other</h3>
 *
 * <ul>
 *   <li>{@link Enums}
 *   <li>{@link MoreObjects}
 *   <li>{@link Preconditions}
 *   <li>{@link StandardSystemProperty}

   *       the same.
   *   <li>The special characters ".", "-", "*", and "_" remain the same.
   *   <li>The space character " " is converted into a plus sign "+".
   *   <li>All other characters are converted into one or more bytes using UTF-8 encoding and each
   *       byte is then represented by the 3-character string "%XY", where "XY" is the two-digit,

  public void testConverterToForward() {
    assertEquals("FooBar", UPPER_UNDERSCORE.converterTo(UPPER_CAMEL).convert("FOO_BAR"));
    assertEquals("fooBar", UPPER_UNDERSCORE.converterTo(LOWER_CAMEL).convert("FOO_BAR"));
    assertEquals("FOO_BAR", UPPER_CAMEL.converterTo(UPPER_UNDERSCORE).convert("FooBar"));
    assertEquals("FOO_BAR", LOWER_CAMEL.converterTo(UPPER_UNDERSCORE).convert("fooBar"));
  }

  public void testConverterToBackward() {

  public void testConverterToForward() {
    assertEquals("FooBar", UPPER_UNDERSCORE.converterTo(UPPER_CAMEL).convert("FOO_BAR"));
    assertEquals("fooBar", UPPER_UNDERSCORE.converterTo(LOWER_CAMEL).convert("FOO_BAR"));
    assertEquals("FOO_BAR", UPPER_CAMEL.converterTo(UPPER_UNDERSCORE).convert("FooBar"));
    assertEquals("FOO_BAR", LOWER_CAMEL.converterTo(UPPER_UNDERSCORE).convert("fooBar"));
  }

  public void testConverterToBackward() {

 *
 * <ul>
 *   <li>All specified safe characters remain unchanged.
 *   <li>If {@code plusForSpace} was specified, the space character " " is converted into a plus
 *       sign {@code "+"}.
 *   <li>All other characters are converted into one or more bytes using UTF-8 encoding and each
 *       byte is then represented by the 3-character string "%XX", where "XX" is the two-digit,

   * (NCR). Any non-ASCII characters appearing in the input will be preserved in the output.
   * Specifically "\r" (carriage return) is preserved in the output, which may result in it being
   * silently converted to "\n" when the XML is parsed.
   *
   * <p>This escaper does not treat surrogate pairs specially and does not perform Unicode
   * validation on its input.
   */
  public static Escaper xmlContentEscaper() {

   * of @JsMethod is to make a method *callable* from JavaScript and (b) this method would not be
   * useful to call from vanilla JavaScript because it returns an instance of Class, which can't be
   * converted to a standard JavaScript type. (Contrast to something like String or boolean.) Since
   * we're not calling it from JavaScript, we suppress the warning.
   */
  @JsMethod
  @SuppressWarnings("unusable-by-js")