fix a bug: transferAsset do not set ref block

Author: zergweak

src/main/java/org/tron/core/services/RpcApiService.java

@@ -561,14 +561,13 @@ public void listNodes(EmptyMessage request, StreamObserver<NodeList> responseObs
     @Override
     public void transferAsset(TransferAssetContract request,
         StreamObserver<Transaction> responseObserver) {
-      ByteString fromBs = request.getOwnerAddress();
-
-      if (fromBs != null) {
-
-        Transaction trx = wallet.createTransaction(request);
-        responseObserver.onNext(trx);
-      } else {
-        responseObserver.onNext(null);
+      try {
+        responseObserver
+            .onNext(createTransactionCapsule(request, ContractType.TransferAssetContract).getInstance());
+      } catch (ContractValidateException e) {
+        responseObserver
+            .onNext(null);
+        logger.debug("ContractValidateException", e.getMessage());
       }
       responseObserver.onCompleted();
     }