Fix PredicateX#map

[alexengrig]

Describe the bug
Cannot resolve method 'map(java.util.function.Function<java.util.Map<? extends K,? extends V>,V>)'

Target
Method: PredicateX#map and MapX#get

Code

class Entry {
    private Map<Integer, String> numbers;
}

<...>

List<String> numbers = entries.stream()
    .filter(PredicateX.of(Entry::getNumbers)
                    // .map(MapX.get(1)) // doesn't work
                    // .map(m -> m.get(1)) // doesn't work
                    .map((Map<Integer, String> m) -> m.get(1)) // works
                    .nonNull())
    .collect(Collectors.toList());