RxJava mapNotNull

RxMapNotNull.kt

/**
 * Applies [transform] to values from the [Observable] and forwards values with non-null results.
 */
inline fun <T : Any, S : Any> Observable<T>.mapNotNull(
    crossinline transform: (T) -> S?
): Observable<S> {
    return this
        .flatMap {
            val result = transform(it)
            if (result == null) {
                Observable.empty()
            } else {
                Observable.just(result)
            }
        }
}