This means that the following code won't work from inside an Arquillian OSGi test:
JavaArchive jar = ShrinkWrap.create("test1.jar", JavaArchive.class);
ZipExporter ze = jar.as(ZipExporter.class);
as this requires the import-package of org.jboss.shrinkwrap.api.exporter.

Looking at the API jar, the following packages should probably also be exported:
org.jboss.shrinkwrap.api.container
org.jboss.shrinkwrap.api.formatter
org.jboss.shrinkwrap.api.importer