code: public void unescape(StringBuilder sb, String str) {
          int firstAmp = str.indexOf('&');
          if (firstAmp < 0) {
              sb.append(str);
          } else {
              doUnescape(sb, str, firstAmp);
          }
      }
docs: <p>
  Unescapes the escaped entities in the <code>String</code> passed and writes the result to the
  <code>StringBuilder</code> passed.
  </p>
  
  @param sb
  The <code>StringBuilder</code> to write the results to; assumed to be non-null.
  @param str
  The source <code>String</code> to unescape; assumed to be non-null.
  
  @see #escape(String)
  @see java.lang.StringBuilder