I am trying to define a parent entity and a child collection

public class Parent {
   private Set<Child> children;
}

And the moment I try to remove child, for example, I am getting UnsupportedOperationException due to the reason, that the collection is initialized by Hibernate as PersistentSet which is immutable and clear() or remove() methods throw this exception.

import io.quarkus.hibernate.orm.panache.PanacheRepository;
import jakarta.enterprise.context.ApplicationScoped;
import jakarta.transaction.Transactional;
import java.util.List;
import java.util.Optional;
import java.util.UUID;

@ApplicationScoped
@Transactional(Transactional.TxType.REQUIRED)
public class SubscriptionRepository implements PanacheRepository<SubscriptionEntity> {

And I have the following code : which returns different errors as follows :

            // Step 2: Copy the child collection to a new mutable Set
            Set<SubscriptionLicenseEntity> currentLicenses = existing.getLicenses();
            Set<SubscriptionLicenseEntity> updatedLicenses = new HashSet<>(currentLicenses);

            // Step 3: Remove the elements you want from the copied Set
            // For example, removing the first element
            Optional<SubscriptionLicenseEntity> licenseToRemove = updatedLicenses.stream().findFirst();
            if (licenseToRemove.isPresent()) {
                updatedLicenses.remove(licenseToRemove.get());

                // If the entity is managed (attached), delete the license directly
                subscriptionLicenseRepository.delete(licenseToRemove.get());
            }

            // Step 4: Reassign the updated collection back to the parent entity
            existing.setLicenses(updatedLicenses);  // Reassign the modified set

/*
Throws : .hibernate.HibernateException: A collection with cascade="all-delete-orphan" was no longer referenced by the owning entity instance: com.qualibooth.entity.SubscriptionEntity.licenses

    at    .hibernate.engine.internal.Collections.processDereferencedCollection(Collections.java:98)
    at .hibernate.engine.internal.Collections.processUnreachableCollection(Collections.java:49)
    at .hibernate.event.internal.AbstractFlushingEventListener.lambda$flushCollections$1(AbstractFlushingEventListener.java:265)
    at .hibernate.engine.internal.StatefulPersistenceContext.forEachCollectionEntry(StatefulPersistenceContext.java:1114)
*/



            // Step 2: Get the existing collection (do not create a new collection)
            Set<SubscriptionLicenseEntity> currentLicenses = existing.getLicenses();

            // Step 3: Remove the elements directly from the existing collection
            Optional<SubscriptionLicenseEntity> licenseToRemove = currentLicenses.stream().findFirst();
            if (licenseToRemove.isPresent()) {
                SubscriptionLicenseEntity license = licenseToRemove.get();
                currentLicenses.remove(license);  // Remove directly from the existing collection

                // Step 4: Delete the license entity from the database
                subscriptionLicenseRepository.delete(license);
            }

 /*
 Throws :  java.lang.UnsupportedOperationException
at java.base/java.util.ImmutableCollections.uoe(ImmutableCollections.java:142)
at java.base/java.util.ImmutableCollections$AbstractImmutableCollection.remove(ImmutableCollections.java:150)
at .hibernate.collection.spi.PersistentSet.remove(PersistentSet.java:212)
 */



            // Step 2: Get the existing licenses
            Set<SubscriptionLicenseEntity> currentLicenses = existing.getLicenses();

            // Step 3: Create a new mutable set and copy the licenses
            Set<SubscriptionLicenseEntity> licensesToRemove = new HashSet<>();
            Optional<SubscriptionLicenseEntity> licenseToRemove = currentLicenses.stream().findFirst();

            if (licenseToRemove.isPresent()) {
                licensesToRemove.add(licenseToRemove.get());

                // Step 4: Remove from the current collection
                currentLicenses.removeAll(licensesToRemove);

                // Step 5: Explicitly delete the orphaned licenses
                licensesToRemove.forEach(subscriptionLicenseRepository::delete);

                // Step 6: Clear the original collection and re-add the modified licenses
                existing.getLicenses().clear();  // Clear the original set
                existing.getLicenses().addAll(currentLicenses);  // Add the updated licenses back
            }

/*
    Throws : java.lang.UnsupportedOperationException
at java.base/java.util.ImmutableCollections.uoe(ImmutableCollections.java:142)
at java.base/java.util.ImmutableCollections$AbstractImmutableCollection.removeAll(ImmutableCollections.java:151)
at .hibernate.collection.spi.PersistentSet.removeAll(PersistentSet.java:291)
 */

            subscriptionRepository.persist(existing);