Submission service cannot be imported to processor

portal/async_celery/submission_processor.py

 import json
 import secrets
 from pathlib import Path
-from typing import Optional
+from typing import Optional, TYPE_CHECKING
 
 from portal import logger
 from portal.database import Project, Submission, SubmissionState, Worker
 from portal.database.enums import WorkerState
 from portal.service import errors
 from portal.storage import UploadedEntity, entities
-from portal.service.submissions import SubmissionsService
+
+if TYPE_CHECKING:
+    from portal.service.submissions import SubmissionsService
 
 log = logger.get_logger(__name__)
 
@@ -20,7 +22,7 @@ class SubmissionProcessor:
         self._services = ServicesCollection()
 
     @property
-    def submission_service(self) -> SubmissionsService:
+    def submission_service(self) -> 'SubmissionsService':
         return self._services.submissions(self.submission)
 
     @property