Px4 class instantiation

Hi, I am new to the PixHawk / PX4 community. I have just begun to review the PX4 software. I see it is written in C++. I see the various classes, such as FlightModeManager (in src/modules/flight_mode_manager/FlightModeManager.cpp and .hpp); but, I do not see the instantiation of the FlightModeManager class. Can someone point me to it or explain how it gets instantiated ?

thanks…