Merge 'develop' changes into 'master'.

src/main/java/fr/unistra/sil/erp/back/controller/api/ApiSubmitTransactionController.java

@@ -60,8 +60,7 @@ public class ApiSubmitTransactionController
         if(t == null)
             throw new ApiBadRequestException("Missing JSON body.");
         
-        if(t.getItem() == null || t.getType() == null ||
-                t.getAmount() == null)
+        if(!t.checkIfValid())
             throw new ApiBadRequestException("Invalid JSON schema.");
         
         System.out.println("Transaction : " + t.getItem() +