This patch brings feature parity with gnome's nm-connection-editor strongswan plugin. Enabling custom proposals is required in order to support connections to strict strong cipher endpoints, the default cipher list doesn't include eg: aes256gcm16-prfsha384-ecp384.
Unit Tests Skipped
I'm not sure the "Cipher Proposals" groupbox should be inside the "Options" groupbox, imo it should be separated groupbox
Same here, probably pointless to set "IKE" and "ESP" when "Enable custom proposals" is false.
Indeed, they should be set only when the "Enable custom proposals" checkbox is checked.