Minor fixes on DMP json export

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

@@ -1135,7 +1135,7 @@ public class DataManagementPlanManager {
         mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
         String fileName = dmp.getLabel();
         fileName = fileName.replaceAll("[^a-zA-Z0-9+ ]", "");
-        File file = new File(fileName);
+        File file = new File(fileName + ".json");
         try {
             mapper.writeValue(file, rdaExportModel);
         } catch (IOException e) {

dmp-backend/web/src/main/java/eu/eudat/models/data/rda/DatasetRDAExportModel.java

@@ -315,7 +315,7 @@ public class DatasetRDAExportModel {
 				if (rdaField.getRdaProperty().equals("dataset.metadata.language")) {
 					metadataRda.setLanguage(rdaField.getRdaValue());
 				}
-				if (rdaField.getRdaProperty().equals("dataset.metadata.metadata_standard_id")) {
+				if (rdaField.getRdaProperty().equals("dataset.metadata.metadata_standard_id") && !rdaField.getRdaValue().isEmpty()) {
 					JSONArray jsonArray = new JSONArray(rdaField.getRdaValue());
 					for (int i = 0; i < jsonArray.length(); i++) {
 						JSONObject jsonObject = jsonArray.getJSONObject(i);