Test.java

@RequestScoped
public class SummaryAccountQueries implements Serializable {
  
  public Optional<SummaryAccountProjection> bad(final SummaryBillingAccount summaryAccount, final UnifiedBillingParty unifiedBillingParty, final LocalDate date) {
        try {
            CriteriaBuilder builder = em.getCriteriaBuilder();
            CriteriaQuery<SummaryAccountProjection> query = builder.createQuery(SummaryAccountProjection.class);
            Root<SummaryAccountProjection> root = query.from(SummaryAccountProjection.class);

            List<Predicate> predicates = new ArrayList<>();
            predicates.add(builder.equal(root.get(SummaryAccountProjection_.summaryAccount), summaryAccount));
            predicates.add(builder.equal(root.get(SummaryAccountProjection_.unifiedBillingParty), unifiedBillingParty));
            predicates.add(builder.equal(root.get(SummaryAccountProjection_.date), date));
            query.where(predicates.toArray(new Predicate[predicates.size()]));
            return Optional.of(em.createQuery(query).getSingleResult());
        }
        catch (NoResultException e) {
            return Optional.empty();
        }
    }

    public Optional<SummaryAccountProjection> good(final SummaryBillingAccount summaryAccount, final UnifiedBillingParty unifiedBillingParty, final LocalDate date) {
        try {
            CriteriaBuilder builder = em.getCriteriaBuilder();
            CriteriaQuery<SummaryAccountProjection> query = builder.createQuery(SummaryAccountProjection.class);
            Root<SummaryAccountProjection> root = query.from(SummaryAccountProjection.class);

            List<Predicate> predicates = new ArrayList<>();
            predicates.add(builder.equal(root.get(SummaryAccountProjection_.summaryAccount), summaryAccount));

            if (unifiedBillingParty != null) {
                predicates.add(builder.equal(root.get(SummaryAccountProjection_.unifiedBillingParty), unifiedBillingParty));
            }
            else {
                predicates.add(builder.isNull(root.get(SummaryAccountProjection_.unifiedBillingParty)));
            }

            predicates.add(builder.equal(root.get(SummaryAccountProjection_.date), date));
            query.where(predicates.toArray(new Predicate[predicates.size()]));
            return Optional.of(em.createQuery(query).getSingleResult());
        }
        catch (NoResultException e) {
            return Optional.empty();
        }
    }
}

In this

predicates.add(builder.equal(root.get(SummaryAccountProjection_.unifiedBillingParty), null));

and

predicates.add(builder.isNull(root.get(SummaryAccountProjection_.unifiedBillingParty)));

Behave differently. Shouldn't an NPE be thrown if passing a null into an equality predicate?