How to solve EI_EXPOSE_REP in records for Lists

Spotbugs raises a warning EI_EXPOSE_REP (May expose internal representation by returning reference to mutable object) for the following code:

public record Example(
    List<String> ex) {

  public Example {
    ex =  List.copyOf(new ArrayList<>(ex));
  }
}

In FindBugs raises a bug called EI_EXPOSE_REP caused by Array something like that is proposed as a solution. But it does not seem to work anymore. Any hints how to resolve that? Is that a bug in Spotbugs? If there is no other way then to suppress it: Is it possible to suppress in on field level instead of on class level?

At the end I will need a solution which also works in a Null - Safe manner. For that I introduced an own copyOf method. Would be great if the solution at the ends work in that null safe manner. (But the Spotbugs warning appears independently if I use my own copyOf method, or the one in java.util.List)

public static <T> List<T> copyOf(List<T> listToCopy) {
    if (listToCopy == null) {
      return Collections.emptyList();
    }
    //noinspection Java9CollectionFactory: cannot be replaced as List.copyOf is not null safe.
    return Collections.unmodifiableList(new ArrayList<>(listToCopy));
}

Does not work with copyOf and also not with unmodifiableList.

Apart from making an immutable copy of the list in the constructor, you also need to update its getter.

public List<String> ex() {
    return Collections.unmodifiableList(ex);
}