OZG-2859 Fall entity.getCreatedBy() == null wird abgefangen

goofy-server/src/main/java/de/itvsh/goofy/historie/HistorieModelAssembler.java

@@ -2,6 +2,7 @@ package de.itvsh.goofy.historie;
 
 import static org.springframework.hateoas.server.mvc.WebMvcLinkBuilder.*;
 
+import java.util.Objects;
 import java.util.Optional;
 import java.util.stream.Stream;
 
@@ -17,6 +18,8 @@ import de.itvsh.goofy.common.user.UserProfileController;
 @Component
 class HistorieModelAssembler implements RepresentationModelAssembler<Command, EntityModel<Command>> {
 
+	private static final String SYSTEM_NOTIFICATION_MANAGER_PREFIX = "system-notification_manager";
+
 	static final String REL_ASSIGNED_TO = "assignedTo";
 
 	static final String ASSIGNED_TO_BODY_FIELD = "assignedTo";
@@ -32,7 +35,7 @@ class HistorieModelAssembler implements RepresentationModelAssembler<Command, En
 	}
 
 	Command unsetSystemUser(Command entity) {
-		if (entity.getCreatedBy().toString().startsWith("system-notification_manager")) {
+		if (Objects.nonNull(entity.getCreatedBy()) && entity.getCreatedBy().toString().startsWith(SYSTEM_NOTIFICATION_MANAGER_PREFIX)) {
 			return entity.toBuilder().createdBy(null).build();
 		}
 

goofy-server/src/test/java/de/itvsh/goofy/historie/HistorieModelAssemblerTest.java

@@ -76,5 +76,12 @@ class HistorieModelAssemblerTest {
 
 			assertThat(model.getLink("createdBy")).isNotPresent();
 		}
+
+		@Test
+		void shouldNotBePresentOnNullValue() {
+			var model = modelAssembler.toModel(CommandTestFactory.createBuilder().createdBy(null).build());
+
+			assertThat(model.getLink("createdBy")).isNotPresent();
+		}
 	}
 }
\ No newline at end of file