ViewModelLiveDataExtension.kt

interface ViewModelLiveDataExtension {
    operator fun <T> LiveData<T>.invoke(value: T) {
        if (this is ViewModelLiveData) {
            val viewModelLiveData = this
            viewModelLiveData.setValue(value)
        }
    }

    fun <T> ViewModel.liveData(value: T? = null) =  lazy {
        ViewModelLiveData<T>().apply { value?.let { setValue(value) } } as LiveData<T>
    }

    private class ViewModelLiveData<T> : LiveData<T>(){
        public override fun setValue(value: T) {
            super.setValue(value)
        }

    }
}