How do I handle null nested objects in RDLC report that is bound to custom assembly object datasource?

I have an RDLC report that I am rendering directly to the Response Stream as PDF (rather than using the ReportViewer). In the code that renders the report, it’s DataSource is bound to a List(Of ClassA) objects defined in a custom assembly. This seems to work for the most part. My problem is that I can’t seem to handle the situation where a nested object is null. For example, given ClassA and ClassB (the nested object) defined as follows: