How do I use other types of key certificates in the setCertPath method

[fuzijianxh]

I successfully used the RSA certificate in the following three methods:

auto policy = TLSPolicy::defaultClientPolicy();
        policy->setCertPath("./client-crt.pem")
            .setKeyPath("./server-key.pem")
            .setCaPath("./ca-crt.pem")
            .setHostname("localhost");
        client[i]->enableSSL(policy);

but encountered loading failure with the SM2 certificate.