This is what Google says on https://developer.android.com/studio/intro/studio-config.html:
A copy of the latest OpenJDK comes bundled with Android Studio 2.2 and higher, and this is the JDK version we recommend you use for your Android projects.
So if you are using the newest version, you won’t need any additional JDK. Furthermore, the official installation instructions don’t include anymore any hints towards the JDK, compared to June 2016.