LiveDataCallAdapterFactory.kt

class LiveDataCallAdapterFactory: CallAdapter.Factory() {
    override fun get(returnType: Type, annotations: Array<Annotation>, retrofit: Retrofit): CallAdapter<*, *>? {
        val observableType =
            CallAdapter.Factory.getParameterUpperBound(0, returnType as ParameterizedType) as? ParameterizedType
                ?: throw IllegalArgumentException("resource must be parameterized")
        return LiveDataCallAdapter<Any>(CallAdapter.Factory.getParameterUpperBound(0, observableType))
    }
}