Resolve "Fixing Problem with duplicate Entry in Statistics"

Related to #540

src/main/java/at/ac/uibk/gitsearch/web/rest/ElasticSearchManagementResource.java

@@ -151,7 +151,9 @@ public class ElasticSearchManagementResource {
           .noContent()
           .headers(HeaderUtil.createEntityDeletionAlert(APPLICATION_NAME, true, ENTITY_NAME, exerciseIdString))
           .build();
-      } else return ResponseEntity.notFound().build();
+      } else {
+        return ResponseEntity.notFound().build();
+      }
     } catch (IOException e) {
       log.error("Cannot delete {}", exerciseIdString, e);
       return ResponseEntity.internalServerError().build();