Exception when diffing a class which uses primitive arrays (like GregorianCalendar)

[mdoninger]

I get the following exception when i create a diff between two entities which have a Calendar field:

org.springframework.sync.PatchException: Error performing diff:
    at org.springframework.sync.Diff.diff(Diff.java:56)
    at SyncCalendarTest.testCalendarUsage(SyncCalendarTest.java:30)
    at ...
Caused by: java.lang.ClassCastException: [I cannot be cast to [Ljava.lang.Object;
    at org.springframework.sync.Diff.diffNonList(Diff.java:123)
    at org.springframework.sync.Diff.diffNonList(Diff.java:126)
    at org.springframework.sync.Diff.diffList(Diff.java:74)
    at org.springframework.sync.Diff.diff(Diff.java:49)
    ... 27 more

This is caused by the cast to Object[] in the line

diffList(operations, path + "/" + field.getName(), Arrays.asList((Object[]) origValue), Arrays.asList((Object[]) modValue));

however, some array fields in the class GregorianCalendar have the type int, which then can't be casted. So this bug might also be applicable to all other classes which use primitive arrays.