Indeed they have sent out letters stating that patents are in fact void. These have created confusion because it is unclear in the letters whether the patent is void from the date of non-payment, or as at the date of the letter. Article 115 suggests the former is correct but the letters suggest the latter.
It is a strange situation. Most patentees ignore the demand and allow patents to lapse when they are no longer needed. There is no actual instance of enforcement against such non-payment and one can hardly believe Indonesia would seek to become the only country in the world to do this.