Subentities referenced by BaseFieldDefinition field are not duplicated

I have this issue with cloning custom entity and fixed it with MR 53 and custom code.

With entity_clone 2.0.0-beta6 we have isClonable() method in src/EntityCloneClonableField.php which also checks
$field_definition instanceof FieldConfigInterface
But all custom reference fields are instance of BaseFieldDefinition class.
So we need additional changes to this method.

I tried to remove this FieldConfigInterface check, but it adds a lot of not needed fields and caused recursions and "Circular reference detected" errors.

Finally I managed to clone custom entities with:
1. Apply patch from the MR 53 (attached it)
2. Extend EntityCloneClonableField class in the custom module and add hardcoded custom entity types check.

Example with 2 files:

1. File modules/custom/my_module/src/MyModuleServiceProvider.php

<?php

namespace Drupal\my_module;

use Drupal\Core\DependencyInjection\ContainerBuilder;
use Drupal\Core\DependencyInjection\ServiceProviderBase;

/**
 * Overrides EntityCloneClonableField class.
 */
class MyModuleServiceProvider extends ServiceProviderBase {

  /**
   * {@inheritdoc}
   */
  public function alter(ContainerBuilder $container) {
    if ($container->hasDefinition('entity_clone.clonable_field')) {
      /** @var \Symfony\Component\DependencyInjection\Definition $definition */
      $definition = $container->getDefinition('entity_clone.clonable_field');
      $definition->setClass('Drupal\my_module\EntityCloneClonableField');
    }
  }

}

2. File modules/custom/my_module/src/EntityCloneClonableField.php

<?php

namespace Drupal\my_module;

use Drupal\Core\Field\BaseFieldDefinition;
use Drupal\Core\Field\EntityReferenceFieldItemListInterface;
use Drupal\Core\Field\FieldDefinitionInterface;
use Drupal\Core\Field\FieldItemListInterface;
use Drupal\entity_clone\EntityCloneClonableField as EntityCloneClonableFieldSource;

/**
 * Manage entity clone clonable field.
 */
class EntityCloneClonableField extends EntityCloneClonableFieldSource {

  /**
   * {@inheritDoc}
   */
  public function isClonable(FieldDefinitionInterface $field_definition, FieldItemListInterface $field): bool {
    $isClonable = parent::isClonable($field_definition, $field);

    // Add custom entities fields as clonable.
    $customClonableEntityTypes = [
      'custom_entity_1',
      'custom_entity_2',
    ];
    if (!$isClonable && in_array($field_definition->getTargetEntityTypeId(), $customClonableEntityTypes)
      && $field_definition instanceof BaseFieldDefinition
      && $field instanceof EntityReferenceFieldItemListInterface && $field->count() > 0) {
      return TRUE;
    }

    return $isClonable;
  }

}

There is one more place, where the field key variable needs to be changed: /src/EntityClone/Content/ContentEntityCloneFormBase.php line 205
Or in human terms: The part of the content clone form, which displays referenced entities for which cloning is enforced.