I updated Jenkins from 2.19.4 to 2.60.1. Then I cannot use 'SSH Plugin' anymore.
On already configured 'SSH sites' in admin configuration, I have an 'ERROR' link under 'User Name' field. clicking on it gives a stack trace with
java.lang.ClassNotFoundException: sun.reflect.ConstructorAccessorImpl coming from com.jcraft.jsch.jce.AES256CTR.init,...javax.crypto.Cipher.chooseProvider...
When adding a new SSH site configuration, the same error appears when losing focus (by clicking somewhere else) while editing the 'User Name' field.