Spring Boot & JPA: CriterialBuilder check if String contains Expression<String> - spring-boot

Question

1.) I want to get an Expression using an Expression and a String Pattern.
It should become true if the Expression is included in the String Pattern not the other way.
The string pattern can look like "MFD" or "MF" or any other combination of the three letters M,F,D. The Expression is either M, F or D.
So far I have the following code, but i think there is a better solution.
public class AthleteSpecification implements Specification<Athlete> {
private String gender;
public AthleteSpecification(String gender) {
super();
this.gender = gender;
}
#Override
public Predicate toPredicate(Root<Athlete> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
Predicate p = cb.disjunction();
if (this.gender == null) {
return cb.conjunction();
} else {
Expression<Boolean> isMaleOrFemaleorDivers;
if (this.gender != null) {
// This is a working solution but not nice
Expression<Boolean> isMale = cb.equal(root.get("gender"), gender.contains("M") ? "M" : "");
Expression<Boolean> isMaleOrFemale = cb.or(isMale,
cb.equal(root.get("gender"), gender.contains("F") ? "F" : ""));
isMaleOrFemaleorDivers = cb.or(isMaleOrFemale,
cb.equal(root.get("gender"), gender.contains("D") ? "D" : ""));
// This is not a solution because i think it only checks if the String is in the Expression<String> not the other way
// Expression<Integer> test = cb.locate(root.get("gender"), gender);
// isMaleOrFemaleorDivers = cb.greaterThan(test, 0);
} else {
isMaleOrFemaleorDivers = cb.conjunction();
}
p.getExpressions().add(cb.and(isNameMatching, isMaleOrFemaleorDivers));
return p;
}
}
}