The method:
putEntry(ArchiveOutputStream, String, FileMode, ObjectLoader)
is deprecated in favor of:
putEntry(ArchiveOutputStream, ObjectId, String, FileMode, ObjectLoader)
since [1].
We don't have an ObjectId in the context in which we call this method,
so just pass null, which is what the implementation of the deprecated
method does anyway.
[1] https://git.eclipse.org/r/#/c/91116/
Change-Id: Ic4f730d50f0f72f8bfad18a4f9c60099856febc4