@Override
  @NotNull
  public XmlDocument getDocument() {
    // this needs to be a seperate child element because of com.intellij.util.xml.impl.ExternalChangeProcessor.visitDocumentChanged()
    final XmlDocument document = findChildByClass(XmlDocument.class);
    assert document != null;
    return document;
  }
@Override
  @NotNull
  public XmlDocument getDocument()