JPA CriteriaBuilder with Sub-String Matching

PersonSpecification.java

// Take sub-string before first space ' ' if there is any or else take the whole string
private static Expression<String> nameSplit(
  Root<Person> root, 
  CriteriaBuilder builder, 
  SingularAttribute<Person, String> str
) {
  Expression<Integer> indexStart = builder.literal(1);
  Expression<Integer> indexOfFirstSpace = builder.locate(root.get(str), " ");
  Expression<Integer> stringLength = builder.length(root.get(str));
  // if indexOfFirstSpace = 0, then no space ' ' is found
  Predicate notFound = builder.equal(indexOfFirstSpace, builder.literal(0));
  // indexEnd = index of the first space ' ' or whole string if there isn't any space ' '
  Expression<Integer> indexEnd = builder.<Integer>selectCase().when(notFound, stringLength).otherwise(indexOfFirstSpace);
  return builder.trim(builder.substring(root.get(str), indexStart, indexEnd));
}

private static Expression<String> firstNameSplit(final Root<Person> root, final CriteriaBuilder builder) {
  return nameSplit(root, builder, Person_.firstNameNormalized);
}

public static Specification<Person> getSpecificationByFilter(SimilarPersonFilter filter) {
  return (root, query, builder) -> SimilarOrganisationSpecification.buildCompetitionEntryFilterPredicate(filter, root, query, builder);
}

private static Predicate buildCompetitionEntryFilterPredicate(
  SimilarPersonFilter filter,
  Root<Organisation> root,
  CriteriaQuery<?> query,
  CriteriaBuilder builder
) {
  List<Predicate> orPredicates = new ArrayList<>();
  Expression<String> fistNameSplit = firstNameSplit(root, builder);
  orPredicates.add(builder.and(
    builder.equal(fistNameSplit, filter.getFirstNameNormalizedSplit()),
    builder.equal(root.get(Person_.lastNameNormalized), filter.getLastNameNormalized()),
    root.get(Person_.dateOfBirth).in(filter.getDateOfBirth())
  ));
  // other predicates
  query.distinct(true);
  return builder.or(toArray(orPredicates));
}  

private static Predicate[] toArray(List<Predicate> predicates) {
  return predicates.toArray(new Predicate[0]);
}