OptimisticLockingFailureException is not thrown by spring data couchbase

Question

I am trying to migrate my application from spring boot 2.2.6 to 2.3.6. This update also updates the spring-data-couchbase 3.2.6 to 4.0.2. Earlier version was throwing OptimisticLockingFailureException but with this upgrade the exception is never thrown. I am using the debugger to stop the execution just before persisting, then changing the data manually in couchbase UI and continue the execution. Exception is thrown in spring-data-couchbase 3.2.6 but not in 4.0.2

spring-data-couchbase 3.2.6

CouchbaseConfiguration.java

@Configuration
@EnableCouchbaseRepositories
public class CouchbaseConfiguration extends AbstractCouchbaseConfiguration {

    @Value("${couchbase.cluster.bucketName}")
    private String bucketName;

    @Value("${couchbase.cluster.ip}")
    private String ip;

    @Value("${couchbase.cluster.password}")
    private String password;

    @Override
    protected String getBucketName() {
        return bucketName;
    }

    @Override
    protected String getBucketPassword() {
        return this.password;
    }

    @Override
    protected List<String> getBootstrapHosts() {
        return Arrays.asList(ip);
    }

    @Bean(name = BeanNames.COUCHBASE_TEMPLATE)
    @Override
    public CouchbaseTemplate couchbaseTemplate() throws Exception {

        final CouchbaseTemplate template = super.couchbaseTemplate();
        template.setWriteResultChecking(WriteResultChecking.EXCEPTION);
        return template;
    }

    @Override
    protected Consistency getDefaultConsistency() {
        return Consistency.READ_YOUR_OWN_WRITES;
    }

PersistenceSnippet.java

    entity = repository.findById(id)
    try {
      return Optional.of(repository.save(entity)); // stop execution here in debugger
    } catch (OptimisticLockingFailureException e) {
      log.warn("failed to persist optimistically");
      return Optional.empty();
    }

spring-data-couchbase 4.0.2

CouchbaseConfiguration.java

@Configuration
@EnableCouchbaseRepositories
public class CouchbaseConfiguration extends AbstractCouchbaseConfiguration {
    @Value("${couchbase.cluster.bucketName}")
    private String bucketName;

    @Value("${couchbase.cluster.ip}")
    private String ip;

    @Value("${couchbase.cluster.password}")
    private String password;

    @Value("${couchbase.durability:lenient}")
    private String durability;

    @Override
    public String getConnectionString() {
        return ip;
    }

    @Override
    public String getUserName() {
        return bucketName;
    }

    @Override
    public String getPassword() {
        return password;
    }

    @Override
    public String getBucketName() {
        return bucketName;
    }

Is it because of the difference of template.setWriteResultChecking(WriteResultChecking.EXCEPTION);? But couchbase template in 4.0.2 does not have any such method. Is there any configuration I am missing in 4.0.2 to be able to throw OptimisicLockingFailureExpception? My Entity object has @Version long version; and @Document annotations