Combined Transformation of LiveData(s) using MediatorLiveData

CombinedTransformation.kt

class CombinedTransformation<T>(
    vararg liveData: LiveData<*>,
    private val onAllChanged: (data: List<Any?>) -> T
) : MediatorLiveData<T>() {

    private val mLiveDataList: MutableList<Any?> = MutableList(liveData.size) { null }

    init {
        liveData.forEachIndexed { index, liveDatum ->
            super.addSource(liveDatum) { datum ->
                mLiveDataList[index] = datum
                value = onAllChanged(mLiveDataList)
            }
        }
    }

}