The pipeline
<p:declare-step xmlns:err="http://www.w3.org/ns/xproc-error" xmlns:p="http://www.w3.org/ns/xproc" version="3.0">
<p:output port="result"/>
<p:http-request href="http://localhost:8246/service/echo" method="post" parameters="map{'override-content-type' : 'application/xml'}">
<p:with-input>
<p:inline content-type="text/plain">{{"key" : "value"}}</p:inline>
</p:with-input>
</p:http-request>
</p:declare-step>
