ViewModel.kt

//... Code removed for brevity

class MainViewModel(private val repository: Repository) : ViewModel() {

    private var messageData: MutableLiveData<String>? = null

    fun loadData(): LiveData<String>?{
        if(messageData == null){
            messageData = MutableLiveData()
        }

        // Getting message from repository class
        messageData!!.postValue( repository.getMessage())
        return messageData
    }
}