* @param noRelation if true, then no relationship is added.
* @return the created child POIXMLDocumentPart
*/
protected final POIXMLDocumentPart createRelationship(POIXMLRelation descriptor, POIXMLFactory factory, int idx, boolean noRelation){
try {
PackagePartName ppName = PackagingURIHelper.createPartName(descriptor.getFileName(idx));
PackageRelationship rel = null;
PackagePart part = packagePart.getPackage().createPart(ppName, descriptor.getContentType());
if(!noRelation) {
/* only add to relations, if according relationship is being created. */
rel = packagePart.addRelationship(ppName, TargetMode.INTERNAL, descriptor.getRelation());