improving code

cms/src/main/java/com/project/cms/complaint/Complaint.java

...n/java/com/project/cms/complaint/ComplaintController.java

...n/java/com/project/cms/complaint/ComplaintRepository.java

...va/com/project/cms/complaint/ComplaintRepositoryImpl.java

...main/java/com/project/cms/complaint/ComplaintService.java

.../java/com/project/cms/complaint/ComplaintServiceImpl.java

cms/src/main/java/com/project/cms/complaint/Staff.java

.../com/project/cms/notification/NotificationController.java

...ava/com/project/cms/notification/NotificationService.java

cms/src/main/resources/sql/schema.sql

...main/resources/templates/complaint/viewAllComplaints.html

cms/src/main/resources/templates/fragments/header.html

...in/resources/templates/notification/notificationForm.html