if (this.getPartsByRelationshipType(
PackageRelationshipTypes.CORE_PROPERTIES).size() == 0) {
logger.debug("Save core properties part");
// We have to save the core properties part ...
new ZipPackagePropertiesMarshaller().marshall(
this.packageProperties, zos);
// ... and to add its relationship ...
this.relationships.addRelationship(this.packageProperties
.getPartName().getURI(), TargetMode.INTERNAL,
PackageRelationshipTypes.CORE_PROPERTIES, null);