centerDocked constant
Centered FloatingActionButton, floating over the Scaffold.bottomNavigationBar so that the center of the floating action button lines up with the top of the bottom navigation bar.
If the value of Scaffold.bottomNavigationBar is a BottomAppBar, the bottom app bar can include a "notch" in its shape that accommodates the overlapping floating action button.
This is unlikely to be a useful location for apps that lack a bottom navigation bar.
Implementation
static const FloatingActionButtonLocation centerDocked = _CenterDockedFabLocation();