[DS-3003] Ensure all service & DAO implementations have a protected constructor

dspace-api/src/main/java/org/dspace/eperson/GroupServiceImpl.java

@@ -65,6 +65,10 @@ public class GroupServiceImpl extends DSpaceObjectServiceImpl<Group> implements
     @Autowired(required = true)
     protected AuthorizeService authorizeService;
 
+    protected GroupServiceImpl()
+    {
+        super();
+    }
 
     @Override
     public Group create(Context context) throws SQLException, AuthorizeException {