should exception's inner class be public or private

Question

Scenario: I have 1 APEX class, in which I have inner class extending exception, as can be seen below:

public with sharing class ClassA{
   PUBLIC/PRIVATE class ClassBException extends ClassCException {}
}

This ClassBException is only used for ClassA, and ClassA will in turn be used in LWC.

Question: The access modifier where it is in all caps in above code (PUBLIC/PRIVATE) should be public or private?

Note: this developer guide only talks about method or variable but what about the inner classes especially the exception classes.

Answer 1

From a strictly Object-Oriented Programming perspective, it should be private (which, you can also just omit, as private is the default access). This makes it clear to future code readers/maintainers that this class is only used locally. Functionally speaking, it doesn't matter which access you provide if you only intend to use it in ClassA.