remove xml prefixs and parse xml using groovy xml parser and read values;
<?xml version="1.0"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xml:base="https://my302303-api.s4hana.ondemand.com/sap/opu/odata/sap/API_MKT_CAMPAIGN_SRV/">
<id>https://myxxxxx-api.s4hana.ondemand.com/sap/opu/odata/sap/API_MKT_CAMPAIGN_SRV/Campaigns(guid%27fa163e88-95f5-1eea-83a9-755f929c5e8c%27)/CampaignAssignedTargetGroups</id>
<title type="text">AssignedTargetGroups</title>
<updated>2019-12-05T20:02:45Z</updated>
<author>
<name/>
</author>
<link href="Campaigns(guid%27fa163e88-95f5-1eea-83a9-755f929c5e8c%27)/CampaignAssignedTargetGroups" rel="self" title="AssignedTargetGroups"/>
<entry>
<id>https://myxxxx-api.s4hana.ondemand.com/sap/opu/odata/sap/API_MKT_CAMPAIGN_SRV/AssignedTargetGroups(TargetGroupUUID=guid’fa163e88-95f5-1eea-83a9-6fb993561e87′,CampaignUUID=guid’fa163e88-95f5-1eea-83a9-755f929c5e8c’)</id>
<title type="text">AssignedTargetGroups(TargetGroupUUID=guid’fa163e88-95f5-1eea-83a9-6fb993561e87′,CampaignUUID=guid’fa163e88-95f5-1eea-83a9-755f929c5e8c’)</title>
<updated>2019-12-05T20:02:45Z</updated>
<category term="API_MKT_CAMPAIGN_SRV.AssignedTargetGroupEntityType" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme"/>
<link href="AssignedTargetGroups(TargetGroupUUID=guid’fa163e88-95f5-1eea-83a9-6fb993561e87′,CampaignUUID=guid’fa163e88-95f5-1eea-83a9-755f929c5e8c’)" rel="self" title="AssignedTargetGroupEntityType"/>
<content type="application/xml">
<m:properties xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices">
<d:TargetGroup>134</d:TargetGroup>
<d:TargetGroupUUID>fa163e88-95f5-1eea-83a9-6fb993561e87</d:TargetGroupUUID>
<d:CampaignUUID>fa163e88-95f5-1eea-83a9-755f929c5e8c</d:CampaignUUID>
</m:properties>
</content>
</entry>
</feed>
-------------
<?xml version="1.0"?>
<xsl:stylesheet version="3.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output indent="yes" method="xml" encoding="utf-8"
omit-xml-declaration="yes"/>
<!-- Stylesheet to remove all namespaces from a document -->
<!-- NOTE: this will lead to attribute name clash, if an element contains
two attributes with same local name but different namespace prefix -->
<!-- Nodes that cannot have a namespace are copied as such -->
<!-- template to copy elements -->
<xsl:template match="*">
<xsl:element name="{local-name()}">
<xsl:apply-templates select="@* | node()"/>
</xsl:element>
</xsl:template>
<!-- template to copy attributes -->
<xsl:template match="@*">
<xsl:attribute name="{local-name()}">
<xsl:value-of select="."/>
</xsl:attribute>
</xsl:template>
<!-- template to copy the rest of the nodes -->
<xsl:template match="comment() | text() | processing-instruction()">
<xsl:copy/>
</xsl:template>
</xsl:stylesheet>
----------
<feed base="https://my302303-api.s4hana.ondemand.com/sap/opu/odata/sap/API_MKT_CAMPAIGN_SRV/">
<id>https://myxxxxx-api.s4hana.ondemand.com/sap/opu/odata/sap/API_MKT_CAMPAIGN_SRV/Campaigns(guid%27fa163e88-95f5-1eea-83a9-755f929c5e8c%27)/CampaignAssignedTargetGroups</id>
<title type="text">AssignedTargetGroups</title>
<updated>2019-12-05T20:02:45Z</updated>
<author>
<name/>
</author>
<link href="Campaigns(guid%27fa163e88-95f5-1eea-83a9-755f929c5e8c%27)/CampaignAssignedTargetGroups"
rel="self"
title="AssignedTargetGroups"/>
<entry>
<id>https://myxxxx-api.s4hana.ondemand.com/sap/opu/odata/sap/API_MKT_CAMPAIGN_SRV/AssignedTargetGroups(TargetGroupUUID=guid’fa163e88-95f5-1eea-83a9-6fb993561e87′,CampaignUUID=guid’fa163e88-95f5-1eea-83a9-755f929c5e8c’)</id>
<title type="text">AssignedTargetGroups(TargetGroupUUID=guid’fa163e88-95f5-1eea-83a9-6fb993561e87′,CampaignUUID=guid’fa163e88-95f5-1eea-83a9-755f929c5e8c’)</title>
<updated>2019-12-05T20:02:45Z</updated>
<category term="API_MKT_CAMPAIGN_SRV.AssignedTargetGroupEntityType"
scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme"/>
<link href="AssignedTargetGroups(TargetGroupUUID=guid’fa163e88-95f5-1eea-83a9-6fb993561e87′,CampaignUUID=guid’fa163e88-95f5-1eea-83a9-755f929c5e8c’)"
rel="self"
title="AssignedTargetGroupEntityType"/>
<content type="application/xml">
<properties>
<TargetGroup>134</TargetGroup>
<TargetGroupUUID>fa163e88-95f5-1eea-83a9-6fb993561e87</TargetGroupUUID>
<CampaignUUID>fa163e88-95f5-1eea-83a9-755f929c5e8c</CampaignUUID>
</properties>
</content>
</entry>
</feed>