I've done some work porting Drools 6.0.1.Final to work on Android. My current effort uses Dex classloaders for all generated classes. Precompiled rule packages execute on Android with either java or mvel dialect.
-Dex classloaders for all generated classes
-Roboguice integration for injecting knowledge bases from precompiled packages
-Maven plugin which pre-compiles rule packages
-Android 5.0 support requires change in mvel2. android 5 doesn't allow overriding the java.version system property. mvel needs to look for an alternate property if that one is not available. One which can be set. I am preparing a pull request for this.
-using KieClasspathContainer depends on my pull request to maven-android-plugin to not strip out kmodule.xml and other meta inf resources
-multiple kjars in dependencies will clobber each other's kmodule.xml. as all jars are merged into a single apk.
I am wondering how to move forward and contribute this code. I think it would be ideal if the same codebase worked on both desktop and android platforms. Otherwise it would need to be a seperate fork. Also how to manage unit testing in the Android version. Any thoughts welcome.