metadata-related NPEs: empty collection vs null

[aloubyansky]

There is a number of NPEs in EJB3DescriptorHandler currently. The code doesn't expect null as a value of collection-valued metadata properties. I started adding checks for null for now. But it would probably be better to return empty collections?

[starksm64]

From the merged view this is fine. The concern about doing this originally was that invalid objects would result for writing back out, and if you initialize fields to empty non-mutable collections this caused parse errors as jbossxb will use an existing collection from the binding target if one exists.

[aloubyansky]

You mean from the merged view we return empty collections instead of null?

[starksm64]

Yes.