Methods inside ViewModel to grab two LiveData from repository and put them into one MediatorLiveData

MainViewModel.kt

fun getSubjects(): LiveData<List<Subject>>? {
        return sroRepository.getSubjects()
    }

fun getReminders(): LiveData<List<Reminder>>? {
        return sroRepository.getReminders()
    }

fun getAllData(): CombinedSubjectReminders? {
        var ldSubjects = getSubjects()
        var ldReminders = getReminders()

        if (ldSubjects != null && ldReminders != null) {
            return CombinedSubjectReminders(ldSubjects, ldReminders)
        }
        return null
    }