     values are "B" and "Q". If this parameter is null, then
                the "Q" encoding is used if most of characters to be
                encoded are in the ASCII charset, otherwise "B" encoding
                is used.</dd>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>Unicode string containing only US-ASCII characters</dd>
<dt><span class="throwsLabel">Throws:</span></dt>
<dd><code><a href="https://docs.oracle.com/javase/8/docs/api/java/io/UnsupportedEncodingException.html?is-external=tru