hwo to parse sm2 certificate and create class PrivateKey

[flymoondust]

I use this：PrivateKeyInfo privateKeyInfo = PrivateKeyInfo.getInstance(bytesContents);

exception：

java.lang.IllegalArgumentException: failed to construct sequence from byte[]: Extra data detected in stream

	at org.bouncycastle.asn1.ASN1Sequence.getInstance(Unknown Source)
	at org.bouncycastle.asn1.pkcs.PrivateKeyInfo.getInstance(Unknown Source)

[flymoondust]

My real request is to use sm4 encrypt the sm2 Privatekey to create encrypted Privatekey