gen.addCertificatesAndCRLs(certs);
X509AttributeCertificate attrCert = CMSTestUtil.getAttributeCertificate();
X509Store store = X509Store.getInstance("AttributeCertificate/Collection",
new X509CollectionStoreParameters(Collections.singleton(attrCert)), "BC");
gen.addAttributeCertificates(store);
ByteArrayOutputStream bOut = new ByteArrayOutputStream();
OutputStream sigOut = gen.open(bOut, true);
sigOut.write(TEST_MESSAGE.getBytes());
sigOut.close();
CMSSignedDataParser sp = new CMSSignedDataParser(bOut.toByteArray());
sp.getSignedContent().drain();
assertEquals(4, sp.getVersion());
store = sp.getAttributeCertificates("Collection", "BC");
Collection coll = store.getMatches(null);
assertEquals(1, coll.size());
assertTrue(coll.contains(attrCert));
}