presto-spi/src/main/java/io/prestosql/spi/security/Identity.java/Identity/toConnectorIdentity
class Identity:    public ConnectorIdentity toConnectorIdentity(String catalog)
    {
        requireNonNull(catalog, "catalog is null");
        return new ConnectorIdentity(user, principal, Optional.ofNullable(roles.get(catalog)), extraCredentials);
    }