The pipeline
<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
<p:output port="result"/>
<p:identity>
<p:with-input>
<p:inline document-properties="map{'base-uri' : 'http://base-uri' , 'add-prop' : 'some-additional-prop'}">
<doc/>
</p:inline>
</p:with-input>
</p:identity>
<p:add-attribute attribute-value="5" attribute-name="att"/>
<p:cast-content-type content-type="application/xml">
<p:with-input select="p:document-properties(.)"/>
</p:cast-content-type>
</p:declare-step>
Schematron validation
<s:schema xmlns:s="http://purl.oclc.org/dsdl/schematron" queryBinding="xslt2">
<s:ns prefix="j" uri="http://www.w3.org/2005/xpath-functions"/>
<s:pattern>
<s:rule context="/">
<s:assert test="j:map">The document root is not 'map'.</s:assert>
<s:assert test="j:map/j:string[@key='base-uri']/text()='http://base-uri'">Value of element 'base-uri' is not 'http://base-uri'.</s:assert>
<s:assert test="j:map/j:string[@key='add-prop']/text()='some-additional-prop'">Value of element 'add-prop' is not 'some-additional-prop'.</s:assert>
</s:rule>
</s:pattern>
</s:schema>
