Hello Mahi,
Replace in the place of XXX your message Type Name and YYYY your namespace
<?xml version='1.0' encoding='utf-8'?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" encoding="UTF-8"/>
<xsl:template match="/">
<ns0:XXX xmlns:ns0="YYYY">
<xsl:copy-of select="." />
</ns0:XXX>
</xsl:template>
</xsl:stylesheet>
And use this before the graphical mapping