Hi,
I could not find some old plugins that I wanted to install in my new JIRA Environment - so what I did was picked up some jar files of the plugin from the existing JIRA file system and placed them under the plugins/user-installed directory - and then the plugin showed up in my new JIRA instance too in disabled mode which i enabled.
IS THIS A BAD PRACTISE ?
Only reason I did this was because I couldnt find those plugins anymore in marketplace.