Clear memory about mapview

[p-lr]

Hello, that's because this demo keeps into the back stack each and every navigated fragment. If you pop the back stack before navigating to a new fragment (using navController.popBackStack()), and if you perform a manual GC into the profiler, you'll see that the previously allocated memory is freed.
I should probably update the demo, because keeping previous fragments into the back stack isn't that helpful.

[o4061]

I think it will work, thank you