Thanks to this post: https://forums.mirthproject.io/forum/mirth-connect/support/184605-sftp-fails-because-server-wants-ssh-rsa
and @Anthony Master from Mirth Slack:
SFTP in 4.5 dropped support for ssh-rsa algo and a few others. The workaround is to add these two options in each affected SFTP connectpr settings. See nextgenhealthcare/connect#5608 for issue that prompted drop in replacement for jsch.
Another example courtesy of Josh McDonald w/Innovar to address:
Algorithm negotiation fail: algorithmName="cipher.c2s"
I also found I needed this:
