XmlFile:test.xml
  PsiElement(XML_DOCUMENT)
    PsiElement(XML_COMMENT)
      XmlToken:XML_COMMENT_START('<!--')
      XmlToken:XML_COMMENT_END('-->')
    PsiElement(XML_PROLOG)
      <empty list>
    XmlTag:
      PsiErrorElement:Valid XML document must have a root tag
        <empty list>