ParentProjectUID is null when a project set as a subproject

I create a small project, let's  say project A, then I put it in project B as a subproject of project B.

When I query the reporting database, I expected that the ParentProjectUID of project A is ProjectUID of project B, but i got null value for ParentProjectUID of project A.

Does that a right condition?

Regards,

Chrisma Andhika