[RxJava 2] Transformer that implements a map that ignores nulls and continues processing the observable output

MapIgnoreNulls.java

import io.reactivex.Observable;
import io.reactivex.ObservableSource;
import io.reactivex.ObservableTransformer;
import io.reactivex.functions.Function;
import java.util.Optional;

public class MapIgnoreNulls {
    public static <T,R> ObservableTransformer<T,R> create(Function<? super T, ? extends R> mapper) {
        return observable -> observable
            .map(t -> Optional.ofNullable(mapper.apply(t)))
            .filter(Optional::isPresent)
            .map(Optional::get);
    };
}

/*
 * Use it like this:
 *
 * Observable.[...].compose(MapIgnoreNulls::create(v -> {
 *     // Your mapping code that can potentially map v to null.
 *     // If the mapped value is null, then the value is ignored and processing continues
 * }))
 *
 * /