For Android, you can put the JAR file in a separate location if you want, but that plugin’s directory would have to be set up as an Android library project (which has a very particular directory structure) and your application project’s “project.properties” file would have to reference that directory. That’s the 2nd option I posted up above. This is how the Corona library is normally referenced. This is also how you would normally including libraries such as facebook as well.
In either case, you have to change something in your application project to tell the Android build system to include your JAR file. There’s no way around that part.
Now, if you are simply trying to test your plugin JAR file and not include it an app that you want to deploy/publish, then it would be simpler to set up your Android plugin project directory as an application project too. Meaning, that your project directory would be set to build both a JAR file and an APK. When building an APK, all of your plugin source code under the “src” directory would be automatically included. Our “CoronaEnterprise/ProjectTemplates/ads-provider” sample shows an example of this. Notice that it has 2 scripts under that project, where one scripts build the plugin JAR file, and the other script builds an APK.