Static text portlets not exporting their `text` RichText fields

[nutjob4life]

Seen in plone.app.portlets-4.4.5 (part of Plone-5.2.2), when exporting portlets from the GenericSetup tool, static text portlets have a literal error message exported for their text property:

<assignment name="xxx" category="context" key="/" manager="plone.leftcolumn"
type="plone.portlet.static.Static" visible="True">
  <property name="footer"/>
  <property name="header">xxx</property>
  <property name="more_url"/>
  <property name="omit_border">False</property>
  <property name="text">RichTextValue object. (Did you mean &lt;attribute&gt;.raw or &lt;attribute&gt;.output?)</property>
</assignment>

📑 Reproduction

1. Start Plone 5.2.2
2. Create a new Plone site
3. Manage portlets → Left column; "go here" to manage portlets of container itself
4. Add portlet… → Static text portlet
5. Enter portlet title "xxx", body text "yyy"; Save
6. ZMI → portal_setup → Export tab
7. Check ✓ box by "Portlets", then "Export selected steps"

🩺 Expected Results

<assignment name="xxx" category="context" key="/" manager="plone.leftcolumn"
type="plone.portlet.static.Static" visible="True">
  <property name="footer"/>
  <property name="header">xxx</property>
  <property name="more_url"/>
  <property name="omit_border">False</property>
  <property name="text">yyy</property> <!-- or maybe a CDATA section -->
</assignment>

🗺 Context

• Just trying to automate some site setup; starting with an export of a live site and making it part of an add-on package is an easy way to go.
• Imports work fine! 🎉