* Retrieves the PackagePart for the given Relationship
* object. Normally you'll want to go via a content type
* or r:id to get one of those.
*/
protected PackagePart getPackagePart(PackageRelationship rel) {
PackagePartName relName;
try {
relName = PackagingURIHelper.createPartName(rel.getTargetURI());
} catch(InvalidFormatException e) {
throw new InternalError(e.getMessage());
}