ss="returnLabel">Returns:</span></dt>
<dd>A map of trailer fields in which all the keys are in lowercase, regardless of the case they had at the
 protocol level. If there are no trailer fields, yet <a href="../../../jakarta/servlet/http/HttpServletRequest.html#isTrailerFieldsReady--"><code>isTrailerFieldsReady()</code></a> is returning true, the empty map is
 returned.</dd>
<dt><span class="throwsLabel">Throws:</span></dt>
<dd><code><a href="https://docs.oracle.com/javase/8/docs/api/java/lang/IllegalStateEx