Pre 4.8 i used the following line to add a component at runtime.
ConstructObject<UYourComponentType>(UYourComponentType::StaticClass(), this, FName("Name"));
Is now
NewObject<UYourComponentType>(this, UYourComponentType::StaticClass(), FName("Name"), RF_NoFlags);
You wont get a error if you dont change it but it gets rid of some warnings.