private static byte[] join(byte[] byteArray1, byte[] byteArray2) {
        byte[] bytes = new byte[byteArray1.length + byteArray2.length];
        System.arraycopy(byteArray1, 0, bytes, 0, byteArray1.length);
        System.arraycopy(byteArray2, 0, bytes, byteArray1.length, byteArray2.length);
        return bytes;
    }
Create a InputStream instance from raw PKCS#1 bytes. Raw Java API can't recognize ASN.1 format, so we should
convert it into a pkcs#8 format Java can understand.
oap-server/server-library/library-server/src/main/java/org/apache/skywalking/oap/server/library/server/ssl/PrivateKeyUtil.java