Append xml param input to root node of target xml

I have the source xml file as

<?xml version="1.0" encoding="UTF-8"?>
<ns0:entry xmlns:ns0="http://ift.tt/r5ut6F">
<ns0:content type="application/xml">
    <ns0:properties>
        <ns0:x>qwerty</ns0:x>
        <ns0:y>OREQ</ns0:y>
        <ns0:y>abc</ns0:y>
    </ns0:properties>
</ns0:content>

And my xslt file looks as below

<xsl:stylesheet xmlns:xsl="http://ift.tt/tCZ8VR" version="1.0">
<xsl:output method="xml" indent="yes"/>
<xsl:strip-space elements="*"/> 
<xsl:param name="documentXML" />
<xsl:variable name="temp" select="document('documentXML')"/>
<xsl:variable name="tempLink" select="$temp/entry"/>
<xsl:template match="@* | node()">
 <xsl:copy>
<xsl:apply-templates select="@* , node()"/>
</xsl:copy>
</xsl:template>

 <xsl:template match="entry">
 <xsl:copy>
 <xsl:apply-templates select="$tempLink" />
 </xsl:copy>
 </xsl:template>

 </xsl:stylesheet>

The parameter above documentXML is passed as

<?xml version="1.0" encoding="UTF-8"?>
<ns0:entry xmlns:ns0="http://ift.tt/r5ut6F">
<ns0:link href="GetArtefactDetailsSet(ArtefactId)/EScHeaderSet" rel="http://ift.tt/1zpiEkw" title="application/atom+xml;type=feed" type="EScHeaderSet">
    <ns0:inline>
        <ns0:feed/>
    </ns0:inline>
</ns0:link>
</ns0:entry>

Note that all this process is being run in tibco and the isXMLDocument flag for documentXML parameter is true()

I am getting below error when running it The [javax.xml.transform.TransformerException] occurred during XSLT transformation: javax.xml.transform.TransformerException: com.tibco.xml.xquery.ExprException: java.lang.NullPointerException

Also when i tried to just copy the document(paramValue) in the target xml it returned MalformedURLException : no protocol.

I have been stuck in this for few days need to get this done desperately. The resultant xml should be like this

<?xml version="1.0" encoding="UTF-8"?>
<ns0:entry xmlns:ns0="http://ift.tt/r5ut6F">
<ns0:link href="GetArtefactDetailsSet(ArtefactId)/EScHeaderSet" rel="http://ift.tt/1zpiEkw" title="application/atom+xml;type=feed" type="EScHeaderSet">
    <ns0:inline>
        <ns0:feed/>
    </ns0:inline>
</ns0:link>
<ns0:content type="application/xml">
    <ns0:properties>
        <ns0:x>qwerty</ns0:x>
        <ns0:y>OREQ</ns0:y>
        <ns0:z>abc</ns0:z>
    </ns0:properties>
</ns0:content>
</ns0:entry>