code: @Nonnull
      public BugInstance addClass(@SlashedClassName(when = When.UNKNOWN)  String className) {
          ClassAnnotation classAnnotation = new ClassAnnotation(ClassName.toDottedClassName(className));
          add(classAnnotation);
          return this;
      }
docs: Add a class annotation. If this is the first class annotation added, it
  becomes the primary class annotation.
  
  @param className
  the name of the class
  @return this object