How to get diff of child Object ? #215

Hi bro !, I'm a newbie with java-object-diff. This library is amazing. But when I new object includes a child object, it cannot get diff.
Ex:
TestChild testChild1 = new TestChild();
testChild1.setId(1);
testChild1.setName("testchild1");

    TestChild testChild2 = new TestChild();
    testChild2.setId(2);
    testChild2.setName("testchild2");

    Test test1 = new Test();
    test1.setId(3);
    test1.setColumnName("test1");
    test1.setTestChild(testChild1);

    Test test2 = new Test();
    test2.setId(4);
    test2.setColumnName("test2");
    test2.setTestChild(testChild2);

when I compare the above object, I receive the result: id: 1->2, name:testchild1 -> testchild2, columnName: test1->test2
where id: 3->4 ( of Test object).

And I cannot know which field is changed by child object, which field is changed by the parent object.

Please help me
thank you very much