The pipeline
<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
<p:output port="result"/>
<p:viewport match="/">
<p:with-input>
<p:inline document-properties="map{'serialization' : map{'indent': true()}, 'prop':'bonus'}">
<doc>
<para>Some para.</para>
</doc>
</p:inline>
</p:with-input>
<p:identity>
<p:with-input port="source">
<p:inline content-type="text/plain">Some new text.</p:inline>
</p:with-input>
</p:identity>
</p:viewport>
<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="http://www.w3.org/1999/xhtml" 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='content-type']/text()='text/plain'">Document's content-type is not text/plain.</s:assert>
<s:assert test="not(j:map/j:string[@key='serialization'])">Serialization properties are not removed.</s:assert>
<s:assert test="j:map/j:string[@key='prop']">Extra property 'prop' is not preserved.</s:assert>
</s:rule>
</s:pattern>
</s:schema>
