* {@code new FIFOEntry(anEntry)} instead of a plain entry object.
 *
 * <pre>
 * class FIFOEntry&lt;E extends Comparable&lt;? super E&gt;&gt;
 *     implements Comparable&lt;FIFOEntry&lt;E&gt;&gt; {
 *   final static AtomicLong seq = new AtomicLong();
 *   final long seqNum;
 *   final E entry;
 *   public FIFOEntry(E entry) {
 *     seqNum = seq.getAndIncrement();

    assertEquals("test & test & test", htmlEscaper().escape("test & test & test"));
    assertEquals("test &lt;&lt; 1", htmlEscaper().escape("test << 1"));
    assertEquals("test &gt;&gt; 1", htmlEscaper().escape("test >> 1"));
    assertEquals("&lt;tab&gt;", htmlEscaper().escape("<tab>"));

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

 * text is performed automatically by the relevant parser.
 *
 * <p>For example, an XML escaper would convert the literal string {@code "Foo<Bar>"} into {@code
 * "Foo&lt;Bar&gt;"} to prevent {@code "<Bar>"} from being confused with an XML tag. When the
 * resulting XML document is parsed, the parser API will return this text as the original literal
 * string {@code "Foo<Bar>"}.
 *

    assertEquals("test & test & test", htmlEscaper().escape("test & test & test"));
    assertEquals("test &lt;&lt; 1", htmlEscaper().escape("test << 1"));
    assertEquals("test &gt;&gt; 1", htmlEscaper().escape("test >> 1"));
    assertEquals("&lt;tab&gt;", htmlEscaper().escape("<tab>"));

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

    assertEquals("xxx", xmlEscaper.escape("xxx"));
    assertEquals("test & test & test", xmlEscaper.escape("test & test & test"));
    assertEquals("test &lt;&lt; 1", xmlEscaper.escape("test << 1"));
    assertEquals("test &gt;&gt; 1", xmlEscaper.escape("test >> 1"));
    assertEquals("&lt;tab&gt;", xmlEscaper.escape("<tab>"));

    // Test all non-escaped ASCII characters.
    String s =
        "!@#$%^*()_+=-/?\\|]}[{,.;:"

    assertEquals("xxx", xmlEscaper.escape("xxx"));
    assertEquals("test & test & test", xmlEscaper.escape("test & test & test"));
    assertEquals("test &lt;&lt; 1", xmlEscaper.escape("test << 1"));
    assertEquals("test &gt;&gt; 1", xmlEscaper.escape("test >> 1"));
    assertEquals("&lt;tab&gt;", xmlEscaper.escape("<tab>"));

    // Test all non-escaped ASCII characters.
    String s =
        "!@#$%^*()_+=-/?\\|]}[{,.;:"

 * {@code new FIFOEntry(anEntry)} instead of a plain entry object.
 *
 * <pre>
 * class FIFOEntry&lt;E extends Comparable&lt;? super E&gt;&gt;
 *     implements Comparable&lt;FIFOEntry&lt;E&gt;&gt; {
 *   final static AtomicLong seq = new AtomicLong();
 *   final long seqNum;
 *   final E entry;
 *   public FIFOEntry(E entry) {
 *     seqNum = seq.getAndIncrement();

      Escapers.builder()
          .addEscape('"', """)
          // Note: "'" is not defined in HTML 4.01.
          .addEscape('\'', "'")
          .addEscape('&', "&")
          .addEscape('<', "&lt;")
          .addEscape('>', "&gt;")
          .build();

  private HtmlEscapers() {}

 * text is performed automatically by the relevant parser.
 *
 * <p>For example, an XML escaper would convert the literal string {@code "Foo<Bar>"} into {@code
 * "Foo&lt;Bar&gt;"} to prevent {@code "<Bar>"} from being confused with an XML tag. When the
 * resulting XML document is parsed, the parser API will return this text as the original literal
 * string {@code "Foo<Bar>"}.
 *

      }
    }

    // Build the content escaper first and then add quote escaping for the
    // general escaper.
    builder.addEscape('&', "&");
    builder.addEscape('<', "&lt;");
    builder.addEscape('>', "&gt;");
    XML_CONTENT_ESCAPER = builder.build();
    builder.addEscape('\'', "&apos;");
    builder.addEscape('"', "&quot;");
    XML_ESCAPER = builder.build();