code: @Nullable
    @ReturnsMutableCopy
    public static ICommonsNavigableSet <EContinent> getContinentsOfCountry (@Nullable final Locale aLocale)
    {
      final Locale aCountry = CountryCache.getInstance ().getCountry (aLocale);
      if (aCountry != null)
      {
        final ICommonsNavigableSet <EContinent> ret = s_aMap.get (aCountry);
        if (ret != null)
          return ret.getClone ();
      }
      return null;
    }
docs: Get all continents for the specified country ID
  
  @param aLocale
  The locale to be used. May be <code>null</code>.
  @return <code>null</code> if no continent data is defined. Otherwise a non-
  <code>null</code> Set with all continents, without
  <code>null</code> elements.