efaulting to the end of the string.</p>
<p>Normalization will:</p>
<ul>
<li>Unescape any <code>%</code>-escapes.</li>
<li>Only allow valid characters (<code>A</code>-<code>Z</code>, <code>a</code>-<code>z</code>, <code>0</code>-<code>9</code>, <code>/</code> and <code>+</code>).</li>
<li>Normalize a <code>_</code> or <code>-</code> character to <code>/</code> or <code>+</code>.</li>
<li>Validate that existing padding (trailing <code>=</code> characters) is correct.</li>
<li>If no padding exists, add correct