With the upcoming release of openLCA 1.7.2 we are removing plugin support, since it was a mostly unused feature and so we wanted to remove necessity to maintain that feature, when moving to a different build platform.
Anyway, if you still want to develop a plugin for 1.7 or 1.7.1 you could take a look at
https://bitbucket.org/msrocka/olca-oekobaudat-plugin - It was the latest plugin that was maintained by us.
In general you need to create an Eclipse RCP Plugin, add the olca-app project as a plugin dependency (it will have the olca-modules as a dependency included and exported). In the plugin.xml of your plugin you can then extend certain extension points, e.g. i/o wizards, editors, menus etc (these are standard eclipse extensions points).
Usually you would create an additional main menu entry from where you open a view or editor (that you have registered as an extension point).
We have also previously developed an example plugin, including documentation, you can find it here:
https://github.com/msrocka/xolca-app-gexf
Hope this helps
