private void appendChartElement(CTGraphicalObjectData data, String id) {
String r_namespaceUri = STRelationshipId.type.getName().getNamespaceURI();
String c_namespaceUri = XSSFDrawing.NAMESPACE_C;
XmlCursor cursor = data.newCursor();
cursor.toNextToken();
cursor.beginElement(new QName(c_namespaceUri, "chart", "c"));
cursor.insertAttributeWithValue(new QName(r_namespaceUri, "id", "r"), id);
cursor.dispose();
data.setUri(c_namespaceUri);
}