Serialize secondary result port in p:xslt

beispiel.xpl

<p:declare-step name="main" version="1.0"
                xmlns:p="http://www.w3.org/ns/xproc">

  <p:xslt name="transformation">
    <p:input port="stylesheet">
      <p:document href="beispiel.xsl"/>
    </p:input>
    <p:input port="source">
      <p:inline>
        <document/>
      </p:inline>
    </p:input>
    <p:input port="parameters">
      <p:empty/>
    </p:input>
  </p:xslt>

  <p:sink/>

  <p:for-each>
    <p:iteration-source>
      <p:pipe step="transformation" port="secondary"/>
    </p:iteration-source>
    <p:store method="html" version="5.0">
      <p:with-option name="href" select="base-uri(/)"/>
    </p:store>
  </p:for-each>

</p:declare-step>

beispiel.xsl

<xsl:transform version="2.0"
               xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:template match="/">
    <xsl:result-document href="foo.html" method="html">
      <h1>Foo</h1>
    </xsl:result-document>
    <xsl:result-document href="bar.html" method="html">
      <h1>Bar</h1>
    </xsl:result-document>
    <h1>Foobar</h1>
  </xsl:template>

</xsl:transform>