* @param anchor the client anchor describes how this frame is attached
* to the sheet
* @return the newly created graphic frame
*/
private XSSFGraphicFrame createGraphicFrame(XSSFClientAnchor anchor) {
CTTwoCellAnchor ctAnchor = createTwoCellAnchor(anchor);
CTGraphicalObjectFrame ctGraphicFrame = ctAnchor.addNewGraphicFrame();
ctGraphicFrame.set(XSSFGraphicFrame.prototype());
long frameId = numOfGraphicFrames++;
XSSFGraphicFrame graphicFrame = new XSSFGraphicFrame(this, ctGraphicFrame);
graphicFrame.setAnchor(anchor);