code: @SuppressWarnings("unchecked")
    protected SortedSet<ScopeService> getRequiredServices() {
      return ImmutableSortedSet.of(
          ScopeService.WINDOW_MANAGER,
          ScopeService.EXEC,
          ScopeService.CORE,
          ScopeService.PREFS,
          ScopeService.SELFTEST,
          ScopeService.CONSOLE_LOGGER,
          ScopeService.COOKIE_MANAGER
      );
    }
docs: A sorted set of required services for this OperaDriver to function.  The services listed will
  be built and initialized in the specified order.
  
  The minimum versions required are defined by the Scope implementation used by this
  OperaDriver.
  
  @return unique set of services to require