Finding ShooterGame AShooterCharacter class definition

On line 320 of ShooterHUD.cpp in the UE4 default ShooterGame example.
AShooterCharacter* MyPawn = Cast(GetOwningPawn());
There is use of the class AShooterCharacter as a pointer, I’ve tried implementing this on a different project, but it needs a definition of the AShooterCharacter class, I can’t find the definition of the class in ShooterHUD.cpp nor ShooterHUD.h

I’ve looked in ShooterWeapon.h and it does not have AShooterCharacter that is accessible with the Health variable. Where is this AShooterCharacter class? Thanks