fix issue with pub api #7326#note-5 the value was a number instaed of search

dmp-backend/web/src/main/java/eu/eudat/logic/managers/DatasetProfileManager.java

@@ -210,7 +210,7 @@ public class DatasetProfileManager {
             return parseItem(listedItems.get(0));
         }
         if (item instanceof Map) {
-            return (String) ((Map)item).get("$");
+            return String.valueOf(((Map)item).get("$"));
         }
         return item != null ? item.toString() : null;
     }