The pipeline
<p:declare-step xmlns:p="http://www.w3.org/ns/xproc" name="pipeline" version="3.0">
<p:output port="result"/>
<p:identity>
<p:with-input>
<p:inline>
<doc/>
</p:inline>
<p:inline content-type="text/html">
<html xmlns="http://www.w3.org/1999/xhtml"/>
</p:inline>
<p:inline content-type="text/plain">This is a text.</p:inline>
<p:inline content-type="application/json">{{"key" : "value"}}</p:inline>
<p:inline content-type="application/octet-stream">0102030405</p:inline>
</p:with-input>
</p:identity>
<p:split-sequence test="if (. instance of document-node()) then ./node()[1] instance of text() and count(./node())=1 else false()" name="splitter"/>
<p:for-each>
<p:identity>
<p:with-input>
<content-type>{p:document-property(., 'content-type')}</content-type>
</p:with-input>
</p:identity>
</p:for-each>
<p:wrap-sequence wrapper="matched" name="matched-sequence"/>
<p:for-each>
<p:with-input pipe="not-matched@splitter"/>
<p:identity>
<p:with-input>
<content-type>{p:document-property(., 'content-type')}</content-type>
</p:with-input>
</p:identity>
</p:for-each>
<p:wrap-sequence wrapper="not-matched" name="not-matched-sequence"/>
<p:wrap-sequence wrapper="result">
<p:with-input pipe="@matched-sequence @not-matched-sequence"/>
</p:wrap-sequence>
</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:pattern>
<s:rule context="/">
<s:assert test="result">Root element is not 'result'.</s:assert>
<s:assert test="result/matched/content-type[1]/text()='text/plain'">Content type is not 'text/plain'.</s:assert>
<s:assert test="result/not-matched/content-type[1]/text()='application/xml'">Content type is not 'application/xml'.</s:assert>
<s:assert test="result/not-matched/content-type[2]/text()='text/html'">Content type is not 'text/html'.</s:assert>
<s:assert test="result/not-matched/content-type[3]/text()='application/json'">Content type is not 'application/json'.</s:assert>
<s:assert test="result/not-matched/content-type[4]/text()='application/octet-stream'">Content type is not 'application/octet-stream'.</s:assert>
</s:rule>
</s:pattern>
</s:schema>