// Two-byte form.
        if (index == end) {
          return false;
        }
        // Simultaneously check for illegal trailing-byte in leading position
        // and overlong 2-byte form.
        if (byte1 < (byte) 0xC2 || bytes[index++] > (byte) 0xBF) {
          return false;
        }
      } else if (byte1 < (byte) 0xF0) {
        // Three-byte form.
        if (index + 1 >= end) {

   *
   */
  public static Escaper urlFormParameterEscaper() {
    return URL_FORM_PARAMETER_ESCAPER;
  }

  private static final Escaper URL_FORM_PARAMETER_ESCAPER =
      new PercentEscaper(URL_FORM_PARAMETER_OTHER_SAFE_CHARS, true);

  /**
   * Returns an {@link Escaper} instance that escapes strings so they can be safely included in <a

 * }</pre>
 *
 * <p>If you wish to avoid this, you should either prepend or append the size of each chunk. Keep in
 * mind that when dealing with char sequences, the encoded form of two concatenated char sequences
 * is not equivalent to the concatenation of their encoded form. Therefore, {@link
 * #putString(CharSequence, Charset)} should only be used consistently with <i>complete</i>
 * sequences and not broken into chunks.
 *

  @Override
  public int hashCode() {
    K k = getKey();
    V v = getValue();
    return ((k == null) ? 0 : k.hashCode()) ^ ((v == null) ? 0 : v.hashCode());
  }

  /** Returns a string representation of the form {@code {key}={value}}. */
  @Override
  public String toString() {
    return getKey() + "=" + getValue();
  }

   * and form of this representation is not guaranteed, except that reparsing its output will
   * produce a {@code CacheBuilderSpec} equal to this instance.
   */
  public String toParsableString() {
    return specification;
  }

  /**
   * Returns a string representation for this CacheBuilderSpec instance. The form of this
   * representation is not guaranteed.
   */

   *
   * <p>The returned supplier is thread-safe. The delegate's {@code get()} method will be invoked at
   * most once unless the underlying {@code get()} throws an exception. The supplier's serialized
   * form does not contain the cached value, which will be recalculated when {@code get()} is called
   * on the deserialized instance.
   *
   * <p>When the underlying delegate throws an exception then this memoizing supplier will keep

    // Ascii.equalsIgnoreCase(), but it is a signal that its documentation may need updating as
    // regards edge cases.

    // The Unicode point {@code 00df} is the lowercase form of sharp-S (ß), whose uppercase is "SS".
    assertEquals("PASSWORD", "pa\u00dfword".toUpperCase()); // [*]
    assertFalse("pa\u00dfword".equalsIgnoreCase("PASSWORD")); // [*]

   *       {@code MapJoiner} method that accepts entries as input, and receive output of the form
   *       {@code key1=A&key1=B&key2=C}.
   *   <li>To output a single entry for each key, pass {@code multimap.asMap()} to a {@code
   *       MapJoiner} method that accepts a map as input, and receive output of the form {@code
   *       key1=[A, B]&key2=C}.
   * </ul>
   *
   * @since 2.0
   */

public abstract class Escaper {
  // TODO(dbeaumont): evaluate custom implementations, considering package private constructor.
  /** Constructor for use by subclasses. */
  protected Escaper() {}

  /**
   * Returns the escaped form of a given literal string.
   *
   * <p>Note that this method may treat input characters differently depending on the specific
   * escaper implementation.
   *
   * <ul>

 * contains information about the named HTML entities such as {@code &} and {@code "} while
 * {@link #escapeUnsafe} is overridden to handle general escaping of the form {@code &#NNNNN;}.
 *
 * <p>The size of the data structure used by {@link ArrayBasedUnicodeEscaper} is proportional to the
 * highest valued code point that requires escaping. For example a replacement map containing the