Why does my application that uses Xerces run into a classloading issue when protected by PicketLink?

Issue

• I am having an issue where my webapp needs to use Xerces 2.10 for its parsing however we also use PicketLink. We are getting the ClassCast issue below when using Xerces 2.10 in our /WEB-INF-lib. Also here is our jboss-deployment-structure.xml including in our webapp.

<jboss-deployment-structure>
    <deployment>
        <exclusions>
            <module name="org.slf4j" />
            <module name="org.slf4j.impl" />
        </exclusions>
        <dependencies>
            <module name="org.picketlink" />
        </dependencies>
    </deployment>
</jboss-deployment-structure>

13:34:19,927 ERROR [org.picketlink.identity.federation] (http-localhost/127.0.0.1:8080-2) PLFED000253: Exception in processing request: java.lang.ClassCastException: org.apache.xerces.parsers.XIncludeAwareParserConfiguration cannot be cast to org.apache.xerces.xni.parser.XMLParserConfiguration
    at org.apache.xerces.parsers.DOMParser.<init>(Unknown Source) [xercesImpl-2.9.1-redhat-1.jar:]
    at org.apache.xerces.parsers.DOMParser.<init>(Unknown Source) [xercesImpl-2.9.1-redhat-1.jar:]
    at org.apache.xerces.jaxp.DocumentBuilderImpl.<init>(Unknown Source) [xercesImpl-2.9.1-redhat-1.jar:]
    at org.apache.xerces.jaxp.DocumentBuilderFactoryImpl.newDocumentBuilder(Unknown Source) [xercesImpl-2.9.1-redhat-1.jar:]
    at __redirected.__DocumentBuilderFactory.newDocumentBuilder(__DocumentBuilderFactory.java:119) [jboss-modules.jar:1.1.2.GA-redhat-1]
    at org.picketlink.identity.federation.core.saml.v2.util.DocumentUtil.getDocument(DocumentUtil.java:201) [picketlink-core-2.1.4.Final.jar:2.1.4.Final]
    at org.picketlink.identity.federation.api.saml.v2.request.SAML2Request.getSAML2ObjectFromStream(SAML2Request.java:163) [picketlink-core-2.1.4.Final.jar:2.1.4.Final]
    at org.picketlink.identity.federation.web.util.IDPWebRequestUtil.getSAMLDocumentHolder(IDPWebRequestUtil.java:123) [picketlink-core-2.1.4.Final.jar:2.1.4.Final]
    at org.picketlink.identity.federation.bindings.tomcat.idp.AbstractIDPValve.processSAMLRequestMessage(AbstractIDPValve.java:505) [picketlink-jbas7-2.1.4.Final.jar:2.1.4.Final]
    at org.picketlink.identity.federation.bindings.tomcat.idp.AbstractIDPValve.invoke(AbstractIDPValve.java:384) [picketlink-jbas7-2.1.4.Final.jar:2.1.4.Final]
    at com.aaa.bbb.ccc.ddd.SSOValve.invoke(SSOValve.java:47) [classes:]
    at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:153) [jboss-as-web-7.1.2.Final-redhat-1.jar:7.1.2.Final-redhat-1]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:155) [jbossweb-7.0.16.Final-redhat-1.jar:]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [jbossweb-7.0.16.Final-redhat-1.jar:]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [jbossweb-7.0.16.Final-redhat-1.jar:]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:368) [jbossweb-7.0.16.Final-redhat-1.jar:]
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [jbossweb-7.0.16.Final-redhat-1.jar:]
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:679) [jbossweb-7.0.16.Final-redhat-1.jar:]