@org.checkerframework.framework.qual.DefaultQualifier(
        org.checkerframework.checker.nullness.qual.Nullable.class)
public class MyException extends Exception {

    public MyException() {}

    public final String getTotalTrace() {
        final StringBuilder sb = new StringBuilder();
        // :: error: (iterating.over.nullable)
        for (StackTraceElement st : getStackTrace()) {
            // :: error: (dereference.of.nullable)
            sb.append(st.toString());
            sb.append(System.lineSeparator());
        }
        return sb.toString();
    }

    @SuppressWarnings("nullness")
    public StackTraceElement[] getStackTrace() {
        throw new RuntimeException("not implemented yet");
    }
}