Missing header and fix unit test failures

api/src/main/java/org/apache/cloudstack/api/response/BackupResponse.java

@@ -1,3 +1,20 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
 package org.apache.cloudstack.api.response;
 
 import com.cloud.serializer.Param;

engine/schema/src/main/java/org/apache/cloudstack/backup/BackupVO.java

@@ -173,7 +173,9 @@ public class BackupVO implements Backup {
         if (StringUtils.isNotBlank(volumes)) {
             String[] strIds = StringUtils.substringBetween(volumes,"[", "]").split(",");
             for (String strId: strIds) {
-                volumeIds.add(Long.valueOf(strId));
+                if (StringUtils.isNotBlank(strId)) {
+                    volumeIds.add(Long.valueOf(strId));
+                }
             }
         }
     }
@@ -186,21 +188,23 @@ public class BackupVO implements Backup {
 
     public void setVolumeIds(List<Long> volumes) {
         if (CollectionUtils.isEmpty(volumes)) {
-            this.volumeIds = new ArrayList<>();
+            volumeIds = new ArrayList<>();
         } else {
-            this.volumeIds = new ArrayList<>(volumes);
+            volumeIds = new ArrayList<>(volumes);
         }
         convertVolumeIdsToString();
     }
 
     private void convertVolumeIdsToString() {
         StringJoiner stringJoiner = new StringJoiner(",", "[", "]");
-        if (CollectionUtils.isNotEmpty(this.volumeIds)) {
-            for (Long volId : this.volumeIds) {
+        if (CollectionUtils.isNotEmpty(volumeIds)) {
+            for (Long volId : volumeIds) {
                 stringJoiner.add(String.valueOf(volId));
             }
+            volumes = stringJoiner.toString();
+        } else {
+            volumes = null;
         }
-        this.volumes = stringJoiner.toString();
     }
 
     protected String getVolumes() {

engine/schema/src/test/java/org/apache/cloudstack/backup/BackupVOTest.java

@@ -43,7 +43,7 @@ public class BackupVOTest {
     @Test
     public void testVolumeIdsEmptyList() {
         vo.setVolumeIds(new ArrayList<>());
-        Assert.assertEquals("[]", vo.getVolumes());
+        Assert.assertEquals(null, vo.getVolumes());
         Assert.assertEquals(new ArrayList<>(), vo.getVolumeIds());
     }
 
@@ -54,8 +54,25 @@ public class BackupVOTest {
     }
 
     @Test
-    public void testDecodeVolumesString() {
+    public void testDecodeVolumesStringNotEmptyList() {
         vo.setVolumes("[1,2,3,4]");
         Assert.assertEquals(ids, vo.getVolumeIds());
     }
+
+    @Test
+    public void testDecodeVolumesStringEmptyList() {
+        vo.setVolumes(null);
+        Assert.assertEquals(new ArrayList<>(), vo.getVolumeIds());
+    }
+
+    @Test
+    public void testSetVolumeIdsMultipleTimes() {
+        List<Long> list = Arrays.asList(1L, 2L);
+        vo.setVolumeIds(list);
+        Assert.assertEquals("[1,2]", vo.getVolumes());
+        vo.setVolumeIds(new ArrayList<>());
+        Assert.assertEquals(null, vo.getVolumes());
+        vo.setVolumeIds(ids);
+        Assert.assertEquals("[1,2,3,4]", vo.getVolumes());
+    }
 }