a #GTlsCertificate
used to interact with the user if necessary
flags which affect the lookup operation
a #GCancellable, or %NULL
a newly allocated issuer #GTlsCertificate, or %NULL. Use g_object_unref() to release the certificate.
GException on failure.
2.30
Look up the issuer of @certificate in the database.
The #GTlsCertificate:issuer property of @certificate is not modified, and the two certificates are not hooked into a chain.
This function can block, use g_tls_database_lookup_certificate_issuer_async() to perform the lookup operation asynchronously.