[GeoNetwork-users] CSW GetRecords POST-Request using XPath

Dear Geonetwork community,

I faced some problems trying to filter a metadata catalog (Geonetwork version 3.4.2.0) through a CSW GetRecords POST-Request using XPaths. My problem is that I'm not sure how to implement XPaths in the request. I tried the following code:

<csw:GetRecords xmlns:csw="http://www.opengis.net/cat/csw/2.0.2&quot; xmlns:gco="http://www.isotc211.org/2005/gco&quot; xmlns:ogc="http://www.opengis.net/ogc&quot; xmlns:gmd="http://www.isotc211.org/2005/gmd&quot; service="CSW" version="2.0.2" resultType="results" outputSchema="csw:IsoRecord" startPosition="1" maxRecords="10">
<csw:Query typeNames="gmd:MD_Metadata">
<csw:Constraint version="1.1.0">
            <ogc:Filter>
                    <ogc:PropertyIsEqualTo>
                        <ogc:PropertyName>/gmd:MD_Metadata/gmd:fileIdentifier/gco:CharacterString</ogc:PropertyName>
                        <ogc:Literal>uuid_value</ogc:Literal>
                    </ogc:PropertyIsEqualTo>
            </ogc:Filter>
        </csw:Constraint>
    </csw:Query>
</csw:GetRecords>

As you can see in the code I simply used the XPath for the <ogc:PropertyName> parameter (as defined in http://portal.opengeospatial.org/files/?artifact_id=20555 Page 154: 10.8.4.11.5 Property references).
The request always leads to 0 results so something has to be wrong with the GetRecords request.

Replacing the XPath with 'Identifier' makes the code work as it should:

<csw:GetRecords xmlns:csw="http://www.opengis.net/cat/csw/2.0.2&quot; xmlns:gco="http://www.isotc211.org/2005/gco&quot; xmlns:ogc="http://www.opengis.net/ogc&quot; xmlns:gmd="http://www.isotc211.org/2005/gmd&quot; service="CSW" version="2.0.2" resultType="results" outputSchema="csw:IsoRecord" startPosition="1" maxRecords="10">
<csw:Query typeNames="gmd:MD_Metadata">
<csw:Constraint version="1.1.0">
            <ogc:Filter>
                    <ogc:PropertyIsEqualTo>
                        <ogc:PropertyName>Identifier</ogc:PropertyName>
                        <ogc:Literal>uuid_value</ogc:Literal>
                    </ogc:PropertyIsEqualTo>
            </ogc:Filter>
        </csw:Constraint>
    </csw:Query>
</csw:GetRecords>

Does anyone know the proper (and most importantly working) way to solve my problem?

Kind regards
David