code: static String buildVirtualPageName(String eventType, Optional<String> objectType,
        String eventName) {
      return Joiner.on("/").skipNulls()
          .join(VIRTUAL_PAGE_PREFIX, eventType, objectType.orNull(), eventName);
    }
docs: Creates a virtual page name (relative URL) from an event type, object type and event name.
  
  @param eventType type or category of the reporting event.
  @param objectType optional type of the object this event applies to.
  @param eventName name of the reporting event.
  @return Virtual page name constructed for this event.