Private nested static class - Good or bad practice?

Question

Would it be considered a bad practice to nest a private static class inside of a non-static class?

public class Outer
{
    private static class Inner
    {
         


        

Answer 1

If the class is used in a multi-threaded application, you may need to control access to the static state via locking. That's a problem with static state whether privately nested or not.