new version features

src/main/java/es/bsc/inb/ades/rest/api/model/DocumentTracking.java

@@ -30,6 +30,7 @@ public class DocumentTracking {
 
 	public DocumentTracking(Long documentId) {
 		this.documentId=documentId;
+		this.trackings = new ArrayList<Tracking>();
 	}
 
 

src/main/java/es/bsc/inb/ades/rest/api/services/DocumentServiceImpl.java

@@ -750,7 +750,8 @@ public class DocumentServiceImpl implements DocumentService {
 	}
 
 	public DocumentTracking findTrackings(Long documentId) {
-		return documentTrackingRepository.findByDocumentId(documentId);
+		DocumentTracking documentTracking = this.findDocumentTrackingById(documentId);
+		return documentTracking;
 	}