What else do I need to check to determine if Class B uses Class A? (Java Reflection)

I have a function that aims to check if Class B uses Class A.

Local variables are not needed.

Currently I am checking for:

1. If Class B extends A
2. The arguments for the constructors of Class B
3. If Class B methods return A
4. The arguments of the methods of Class B
5. The field types of Class B

This problem is like the halting problem. I am I miss anything else?