Can't parse XML through JSTL using Google App Engine

After running my code I get the following error:

HTTP ERROR 500

Problem accessing /index.jsp. Reason:

java.lang.NoClassDefFoundError: org/apache/xpath/XPathException

I correctly declared the taglibs in my index.jsp file:

<%@ taglib prefix="c" uri="http://ift.tt/QfKAz6" %>
<%@ taglib prefix="x" uri="http://ift.tt/O45vfj" %>

Here is where I try to parse the XML file:

<select class="form-control" style="width:40rem;">
    <!-- Open Data -->
    <c:import var="sportInfo" url="http://ift.tt/1NI4n8S"/>
    <x:parse xml="${sportInfo}" var="output"/>
    <x:forEach select="$output/document/data/element/geo/name" var="item">
        <option value="$output/document/data/element/_IDOBJ"><x:out select="$item" /></option>
    </x:forEach>
</select>

I have already checked online and tried different solutions, including adding Xalan to my project's build path, but so far no results.

Thanks in advance.