ActivityViewModelLazy.kt

@MainThread
inline fun <reified VM : ViewModel> ComponentActivity.viewModels(
  noinline factoryProducer: (() -> Factory)? = null
): Lazy<VM> {
  val factoryPromise = factoryProducer ?: {
    defaultViewModelProviderFactory
  }
  return ViewModelLazy(VM::class, { viewModelStore }, factoryPromise)
}