public static Escaper xmlAttributeEscaper() {
    return XML_ATTRIBUTE_ESCAPER;
  }
  private static final Escaper XML_CONTENT_ESCAPER;
  private static final Escaper XML_ATTRIBUTE_ESCAPER;

  static {
    Escapers.Builder builder = Escapers.builder();
    // The char values \uFFFE and \uFFFF are explicitly not allowed in XML

    }
    return result;
  }

  /**
   * Convert this builder into a char escaper which is just a decorator around the underlying array
   * of replacement char[]s.
   *
   * @return an escaper that escapes based on the underlying array.
   */
  public Escaper toEscaper() {
    return new CharArrayDecorator(toArray());
  }

    assertUnicodeEscaping(e, "%F4%8F%BF%BF", '\uDBFF', '\uDFFF');

    // simple string tests
    assertEquals("", e.escape(""));
    assertEquals("safestring", e.escape("safestring"));
    assertEquals("embedded%00null", e.escape("embedded\0null"));
    assertEquals("max%EF%BF%BFchar", e.escape("max\uffffchar"));
  }

  /** Tests the various ways that the space character can be handled */
  public void testPlusForSpace() {

    // Test quotes are escaped.
    assertEquals(""test"", xmlAttributeEscaper.escape("\"test\""));
    assertEquals("'test'", xmlAttributeEscaper.escape("'test'"));
    // Test all escapes
    assertEquals(
        "a&quot;b&lt;c&gt;d&amp;e&quot;f&apos;", xmlAttributeEscaper.escape("a\"b<c>d&e\"f'"));
    // Test '\t', '\n' and '\r' are escaped.

        String escaped3 = SuggestUtil.escapeWildcardQuery(query3);
        assertEquals("test\\*query\\?end", escaped3);

        // Test with no wildcards
        String query4 = "test query";
        String escaped4 = SuggestUtil.escapeWildcardQuery(query4);
        assertEquals("test query", escaped4);

        // Test with multiple wildcards
        String query5 = "***???";

    // Test simple escape of '&'.
    assertEquals("foo&bar", htmlEscaper().escape("foo&bar"));

    // If the string contains no escapes, it should return the arg.
    // Note: assert<b>Same</b> for this implementation.
    String s = "blah blah farhvergnugen";
    assertSame(s, htmlEscaper().escape(s));

    // Tests escapes at begin and end of string.
    assertEquals("&lt;p&gt;", htmlEscaper().escape("<p>"));

    // Test simple escape of '&'.
    assertEquals("foo&bar", htmlEscaper().escape("foo&bar"));

    // If the string contains no escapes, it should return the arg.
    // Note: assert<b>Same</b> for this implementation.
    String s = "blah blah farhvergnugen";
    assertSame(s, htmlEscaper().escape(s));

    // Tests escapes at begin and end of string.
    assertEquals("&lt;p&gt;", htmlEscaper().escape("<p>"));

    }

    /**
     * Escapes specific characters in a query string.
     * Replaces each specified character with its escaped version (prefixed with backslash).
     *
     * @param q the query string to escape
     * @param values the characters to escape
     * @return the escaped query string
     */
    protected String escape(final String q, final String... values) {
        String value = q;

 *
 */
public class JsonUtil {

    /**
     * Defualt constructor.
     */
    protected JsonUtil() {
    }

    /**
     * Escapes a value as Json string.
     *
     * @param value input
     * @return escaped string.
     */
    public static String escape(final String value) {
        if (value == null) {
            return null;
        }

        char c;
        final int len = value.length();

     *   <li>' with &amp;apos;</li>
     * </ul>
     * Additionally, it strips invalid XML characters from the input string.
     *
     * @param value the input string to be escaped
     * @return the escaped XML string with invalid characters removed, or empty string if value is null
     */
    public static String escapeXml(final String value) {
        if (value == null) {
            return StringUtil.EMPTY;