import java.util.List; import java.util.Set; import java.util.stream.Stream; class Validator { static boolean thereAreConstraintViolationsIn1(final Stream objectStream, Validator validator) { Stream>> rStream = objectStream .map(validator::validate); return rStream .flatMap(set -> set.stream()) .findAny() .isPresent(); } static void thereAreConstraintViolationsIn(final Stream objectStream, Validator validator) { Stream>> rStream = objectStream.map(validator ::validate); Stream>> lStream = objectStream.map((a) -> validator.validate(a)); } Set> validate(T var1, Class ... var2) { return null; } }