We were using postfixes to avoid inference problems around operator methods (such as fromIterable vs fromArray) but there is at least one operator currently, startWith, that may exhibit type ambiguity. A dedicated postfixed name should resolve the issue, such as:

1. startWith(T) + startWithIterable(Iterable<T>)
2. startWithItem(T) + startWith(Iterable<T>) + remove startWith(T)
3. startWithItem(T) + startWithIterable(Iterable<T>) + remove startWith(T).

As a preparation, we can deprecate startWith(T) within 2.2.x in case option 2 or 3 is chosen.