code: public String unescape(String str) {
          int firstAmp = str.indexOf('&');
          if (firstAmp < 0) {
              return str;
          } else {
              StringBuilder sb = createStringBuilder(str);
              doUnescape(sb, str, firstAmp);
              return sb.toString();
          }
      }
docs: <p>
  Unescapes the entities in a <code>String</code>.
  </p>
  
  <p>
  For example, if you have called addEntity(&quot;foo&quot;, 0xA1), unescape(&quot;&amp;foo;&quot;) will return
  &quot;\u00A1&quot;
  </p>
  
  @param str
  The <code>String</code> to escape.
  @return A new escaped <code>String</code>.