[SOLVED] I'm trying to get a plugin installed on Eclipse (specifically j2c)

Hello. I installed Eclipse on my Debian 10 machine. This works fine. However, I also tried to get a plugin installed on it, that being j2c. From the README, I placed the jar file (se.arnetheduck.j2c_0.5.0.201309052312.jar) of j2c in the /usr/eclipse/dropins directory. However, I can't find it under "additional software".

So, if anyone out there has experience with installing this plugin on Eclipse, do feel free to share any hints with me. Thank you.