In order to easily implement APK Expansion file support, I added the following libraries offered by Google:
I did exactly as the Android docs describe ("project Properties -> Android -> Add package").
Does this mean that their complete source code (in compiled form, of course) will be included in my final APK? (Actually, my question generally applies to any Android library project, but APK Expansion is a concrete scenario.)
For example, the Google Play Downloader Library has many strings and helper methods. These will be copied into my APK even if I don't use them, I suppose. In other words, unlike the base Android libraries, these Google libraries aren't present on Android devices, are they? Their full content will be present in my app's APK, I guess.
Does this mean that their complete source code (in compiled form, of course) will be included in my final APK?
Yes, for your default debug build. Release builds run through ProGuard, which can rip out some of the unused Java code.
unlike the base Android libraries, these Google libraries aren't present on Android devices, are they?
Correct.