OZG-7426 handle empty/missing file content

vorgang-manager-server/src/main/java/de/ozgcloud/vorgang/files/OzgCloudFileRepository.java

@@ -89,6 +89,9 @@ class OzgCloudFileRepository {
 	}
 
 	private long getContentSize(String contentId) {
+		if (Objects.isNull(contentId)) {
+			return 0;
+		}
 		var contentGridFsFile = gridFsTemplate.find(queryByObjectId(contentId)).first();
 		if (Objects.isNull(contentGridFsFile)) {
 			throw new NotFoundException(GridFSFile.class, contentId);

vorgang-manager-server/src/test/java/de/ozgcloud/vorgang/files/OzgCloudFileRepositoryITCase.java

@@ -100,6 +100,15 @@ class OzgCloudFileRepositoryITCase {
 			assertThat(result.getSize()).isEqualTo(OzgCloudFileTestFactory.SIZE);
 		}
 
+		@Test
+		void shouldSetContentSizeToZero() {
+			var ozgCloudFile = OzgCloudFileTestFactory.createBuilder().id(null).version(0).contentId(null).build();
+
+			var result = repository.save(ozgCloudFile);
+
+			assertThat(result.getSize()).isZero();
+		}
+
 		@Test
 		void shouldFailIfContentMissing() {
 			var ozgCloudFile = OzgCloudFileTestFactory.createBuilder().id(null).version(0).contentId("missing").build();