collection of small fixed to resolve issues after slightly unexpected

src/main/java/nl/tudelft/ewi/queue/DatabaseLoader.java

...ava/nl/tudelft/ewi/queue/controller/CourseController.java

...ava/nl/tudelft/ewi/queue/helper/BrightspaceCsvHelper.java

...ain/java/nl/tudelft/ewi/queue/model/FirstYearStudent.java

src/main/java/nl/tudelft/ewi/queue/model/Group.java

src/main/java/nl/tudelft/ewi/queue/model/Lab.java

...java/nl/tudelft/ewi/queue/model/RequestApprovedEvent.java

...java/nl/tudelft/ewi/queue/model/RequestAssignedEvent.java

.../java/nl/tudelft/ewi/queue/model/RequestCreatedEvent.java

.../nl/tudelft/ewi/queue/model/RequestForwardToAnyEvent.java

...ava/nl/tudelft/ewi/queue/model/RequestForwardedEvent.java

...va/nl/tudelft/ewi/queue/model/RequestProcessingEvent.java

...java/nl/tudelft/ewi/queue/model/RequestRejectedEvent.java

.../java/nl/tudelft/ewi/queue/model/RequestRevokedEvent.java

src/main/java/nl/tudelft/ewi/queue/model/Subscription.java

src/main/java/nl/tudelft/ewi/queue/service/GroupService.java

...l/tudelft/ewi/queue/controller/RequestControllerTest.java

src/test/java/nl/tudelft/ewi/queue/model/LabTest.java