How to I setup javalin with SSL support with browser said it is safe freely?

Hi @LoYungSum. SSL is handled by Jetty, there's an example at io.javalin.examples.HelloWorldSecure.
I know. But it didn't said how to make it become "secure"
After reading it. I still don't know what should I do.
First, I create a file which contains the private key which is named cert.cer.
Then I execute this command
openssl crl2pkcs7 -nocrl -certfile cert.cer -out certificate.p7b
Then I insert the p7b to my keyfile
keytool -import -alias example -trustcacerts -file certificate.p7b -keystore keystroke.jks
But I got this error
keytool error: java.lang.Exception: Input not an X.509 certificate
@LoYungSum This isn't really related to Javalin. Maybe you can post on stack overflow?
Ok.
@LoYungSum this article may help you https://examples.javacodegeeks.com/enterprise-java/jetty/jetty-ssl-configuration-example/ (there's dedicated section on how to configure ssl for embedded jetty which is used by javalin).
But the example still haven't solve the problem for "secure"
http://examples.javacodegeeks.com/wp-content/uploads/2015/06/ssl_im1.jpg