Blackboard variables get removed when renaming the class name

Steps to reproduce:

1. Create and open a behavior graph
2. Add an enum type to the blackboard
3. Change the name of the enum in the script

Actual results: The enum variable is removed from the graph

Expected results: The graph keeps its enum and uses the new name

Reproducible with versions: 1.0.9

Tested on (OS): MacOS

Notes:

• This also happens with Unity.Object class
• If you change it back to its initial name, nodes that referenced it show it but it's not shown in the blackboard