fix null bug in DeleteObjectsResult's constructor.

Author: huiguangjun

src/main/java/com/aliyun/oss/model/DeleteVersionsResult.java

@@ -92,7 +92,9 @@ public void setDeleteMarkerVersionId(String deleteMarkerVersionId) {
     private final List<DeletedVersion> deletedVersions = new ArrayList<DeletedVersion>();
 
     public DeleteVersionsResult(List<DeletedVersion> deletedVersions) {
-        this.deletedVersions.addAll(deletedVersions);
+        if (deletedVersions != null) {
+            this.deletedVersions.addAll(deletedVersions);
+        }
     }
 
     /**

src/test/java/com/aliyun/oss/common/model/ObjectRelatedTest.java

@@ -389,6 +389,11 @@ public void testDeleteVersionsResult() {
         assertEquals("markerId", version.getDeleteMarkerVersionId());
         assertEquals("key", version.getKey());
         assertEquals("versionid", version.getVersionId());
+
+        DeleteVersionsResult result = new DeleteVersionsResult(null);
+
+        List<DeleteVersionsResult.DeletedVersion> deletedVersions = Arrays.asList();
+        result = new DeleteVersionsResult(deletedVersions);
     }
 
     @Test