JSON merge 021(AB)

The pipeline

<p:declare-step xmlns:err="http://www.w3.org/ns/xproc-error"
                xmlns:p="http://www.w3.org/ns/xproc"
                xmlns:t="http://xproc.org/ns/testsuite/3.0" version="3.0">
   <p:output port="result"/>
   <p:json-merge key="[1, 2, 3]">
      <p:with-input expand-text="false">
         <p:inline>
            <xml/>
         </p:inline>
         <p:inline content-type="text/html">
            <html/>
         </p:inline>
      </p:with-input>
   </p:json-merge>
</p:declare-step>