Do we need Jack to use Java 8 features to make a build using Android.mk?

Question

I have an Android.mk file and I was trying to make a build for Android 8.1 where I was using RxJava but while building it, I was getting the error

Lambda coming from jar file need their interfaces on the classpath to be compiled

so, I searched a lot and found that

"ANDROID_COMPILE_WITH_JACK:=false" 

fixes the issue but I want to know how and why it is like that.

Answer 1

I found on https://source.android.com/setup/build/jack that Jack supports Java programming language 1.7 and lambda(in rxJava) is 1.8 feature so is it causing the problem? That is why I need to disable the compilation?