When exporting to JSON export it with pretty text

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

@@ -32,7 +32,7 @@ public class RDAManager {
 		ObjectMapper mapper = new ObjectMapper();
 		mapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss Z"));
 
-		result = mapper.writeValueAsString(rdaDmp);
+		result = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(rdaDmp);
 
 		return result;
 	}