Throw error when notifications via email enabled and no email provide…

…d for new user

src/main/java/org/radarbase/appserver/service/UserService.java

@@ -36,6 +36,7 @@
 import org.radarbase.appserver.repository.ProjectRepository;
 import org.radarbase.appserver.repository.UserRepository;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -50,6 +51,9 @@
 @Slf4j
 public class UserService {
 
+  @Value("${notification.email.enabled:false}")
+  private boolean sendEmailNotifications;
+
   private final transient UserConverter userConverter;
   private final transient UserRepository userRepository;
   private final transient ProjectRepository projectRepository;
@@ -152,6 +156,13 @@ public FcmUserDto saveUserInProject(FcmUserDto userDto) {
               + ". Please use Update endpoint if need to update the user");
     }
 
+    if (sendEmailNotifications && (userDto.getEmailAddress() == null || userDto.getEmailAddress().isEmpty())) {
+        throw new InvalidUserDetailsException(
+            "The option to send notifications via email is enabled. " +
+                "Email Address is required for sending email notifications. " +
+                "Please provide a valid email address.");
+    }
+
     User newUser = userConverter.dtoToEntity(userDto).setProject(project);
     // maintain a bi-directional relationship
     newUser.getUsermetrics().setUser(newUser);