For certain types of XML generation (VoiceXML, for example) it is illegal to have a opening and closing tag for certain tag sets. When using the "Any" component to generate an XML tag that has no body, it generates a closing tag when what it should render is an empty tag.
For example, if in VXML you have:
<var jwcid="@Any" name="myVar" expr="someVal"/>
The Any component generates:
<var name="myVar" expr="someVal"></var>
Which is ignored by most VoiceXML 2.0 compliant browsers. If the tag detected that there were no body present and did a writer.beginEmpty(), all would be well!