Unique constraint violated on replace item from list in test

So I have client = creditor which has list of documents. This list can contain only one type of each document, so i have method add document which adds new documnet, but if there is already document of this type it should be replaced.

this test fail on unique constraint

def "should replace documents with same type"() {
    given:
        def creditor = creditors.create(CreditorHelper.createSampleCreditorForm())
        def documentType = DocumentTypeEvent.INVESTMENT_INSTRUCTION
    and:
        def old = documents.addDocument(new DocumentForm("urlOld", creditor.creditorReference, documentType, ZonedDateTime.now()))

    when:
        documents.addDocument(new DocumentForm("urlNew", creditor.creditorReference, documentType, ZonedDateTime.now()))

    then:
        def newResult = documentRepository.findByCreditorReference(creditor.creditorReference)
        newResult.size() == 1
        newResult.find {
            it.url == "urlNew"
        }
    and:
        documentRepository.findByHash(old.hash) == Optional.empty()
}

implementaion is simple replace:

@Transactional
public Document addDocument(final DocumentForm documentForm) {
    return creditorRepository.findByCreditorReferenceIgnoreCase(documentForm.getCreditorReference())
        .addDocument(new Document(documentForm));
}

above calls:

 public Document addDocument(Document newDocument) {
    documents.removeIf(existingDocument -> existingDocument.getType() == newDocument.getType());
    documents.add(newDocument);
}

entity:

@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
@JoinColumn(name = "creditor_id")
@Builder.Default
private List<Document> documents = new ArrayList<>();

funny is that when I remove unique constraint from flyway test is passing, so it seems like problems with transaction.