how to set the mode of SM2Engine

```
...
Example: 
Cipher sm2Engine1 = Cipher.getInstance("SM2", "BC");
byte[] m = Strings.toByteArray("encryption standard");
// I want to set SM2Engine.mode=C1C3C2 ?
sm2Engine1.init(Cipher.ENCRYPT_MODE, kp.getPublic(), new TestRandomBigInteger("4C62EEFD6ECFC2B95B92FD6C3D9575148AFA17425546D49018E5388D49DD7B4F", 16));
byte[] enc = sm2Engine1.doFinal(m);
...
```