Extra space characters surrounding classes even and odd create warnings with some validation tools

In function theme_nice_menus_build(), space characters surrounding the strings for 'even' and 'odd' can cause problems with some validation tools because "Authors should not declare attribute values with leading or trailing white space" (from http://www.w3.org/TR/html4/types.html#h-6.2 ) In the attached screenshot of output from TotalValidator 8.2.1 warnings are generated on code created by Nice Menus: "W001 There should not be any white space at the start or end of an attribute's value." To resolve this, this function should return output that does not contain trailing white space in the value of the class attribute. These are admittedly only warnings that may be ignored, but it would be ideal if this can be resolved. Here is an example of the code that is generated by Nice Menus:

          <div id="navigation" class="menu">
                              <ul class="nice-menu nice-menu-right nice-menu-04a70bc8673e88c90271411229c6a57b" id="nice-menu-1"><li class="menu-664 menu-path-node-37 active-trail first odd "><a href="/desai/about" class="active">About</a></li>
<li class="menu-665 menu-path-node-38  even "><a href="/desai/people">People</a></li>
<li class="menu-666 menuparent  menu-path-node-39  odd "><a href="/desai/research">Research &amp; Projects</a><ul><li class="menu-671 menu-path-node-44 first odd "><a href="/desai/research/oral-drug-delivery">Oral Drug Delivery</a></li>
<li class="menu-773 menu-path-node-67  even "><a href="/desai/research/transmucosal-drug-delivery">Transmucosal Drug Delivery</a></li>
<li class="menu-736 menu-path-node-45  odd "><a href="/desai/research/ocular-drug-delivery">Ocular Drug Delivery</a></li>
<li class="menu-737 menu-path-node-46  even "><a href="/desai/research/cell-encapsulation-and-delivery">Cell Encapsulation and Delivery</a></li>
<li class="menu-738 menu-path-node-47  odd "><a href="/desai/research/cardiac-tissue-engineering">Cardiac Tissue Engineering</a></li>
<li class="menu-739 menu-path-node-48  even "><a href="/desai/research/vascular-stents">Vascular Stents</a></li>
<li class="menu-741 menu-path-node-49  odd "><a href="/desai/research/dental-stem-cell-engineering">Dental Stem Cell Engineering</a></li>
<li class="menu-774 menu-path-node-68  even "><a href="/desai/research/osteomyelitis">Bone Drug Delivery</a></li>
<li class="menu-742 menu-path-node-50  odd last"><a href="/desai/research/corneal-tissue-engineering">Epithelial Tissue Engineering &amp; Drug Delivery</a></li>
</ul></li>
<li class="menu-670 menu-path-node-43  even "><a href="/desai/publications">Publications</a></li>
<li class="menu-667 menu-path-node-40  odd "><a href="/desai/facility">Facility</a></li>
<li class="menu-772 menu-path-node-66  even "><a href="/desai/teaching">Teaching</a></li>
<li class="menu-668 menu-path-node-41  odd last"><a href="/desai/contact">Contact Us</a></li>
</ul>
                          
      </div>