default Dtor<S, T> targetFilter(final Predicate<? super T> predicate) {
		requireNonNull(predicate);
		return source -> unapply(source).filter(predicate);
	}
Create a new {@code Extractor} by filtering the sub-elements. If the
given {@code predicate} doesn't match, the created extractor will filter
these sub-elements

@param predicate the sub-element {@code predicate}
@return a new {@code Extractor} which filters on the sub-elements
@throws NullPointerException if the given {@code predicate} is {@code null}
jenetics.incubator/src/main/java/io/jenetics/incubator/beans/internal/Dtor.java