AsyncResult.mapEmpty

Map the result of this async result to {@code null}.<p>

This is a convenience for {@code asyncResult.map((T) null)} or {@code asyncResult.map((Void) null)}.<p>

When this async result succeeds, {@code null} will succeeed the async result returned by this method call.<p>

When this async result fails, the failure will be propagated to the returned async result.

@return the mapped async result