upd: added find by registered user for getting deviceId on front end

src/main/java/com/backend/glowhouse/repository/device/DeviceRepository.java

@@ -3,7 +3,11 @@ package com.backend.glowhouse.repository.device;
 import com.backend.glowhouse.model.Device;
 import org.springframework.data.mongodb.repository.MongoRepository;
 
+import java.util.Optional;
+
 public interface DeviceRepository extends MongoRepository<Device, String>, DeviceRepositoryCustom {
 
-    public Device findByDeviceId(String deviceId);
+    Device findByDeviceId(String deviceId);
+
+    Device findByRegisteredUser(String username);
 }