Replace the runtime module with one developed in the clean room in order to license it under Apache License 2.0

[gfx]

Currently runtme/ is licensed under GPL v2 + CE. Android OS doesn't use classpath, so "classpath exception" makes no sense in Android.

Unfortunately, I can't because my brain is no longer the clean room, so all I can do is just waiting for pull-requests.

To Contributors

You must not read the OpenJDK source code as well as AOSP's because it's under GPL v2.

All you can do is to read the reference manual, for example:

• https://developer.android.com/reference/java/util/Optional.html
• https://developer.android.com/reference/java/util/function/package-summary.html

[gfx]

https://www.reddit.com/r/androiddev/comments/69rvf4/retropiler_java8_standard_library_for_android_sdk/

[gfx]

Firstly, I have removed the files under GPLv2+CE on the develop branch: https://github.com/retropiler/retropiler/tree/develop