ChatServer.kt

private fun startAdvertisement() {
        advertiser = adapter.bluetoothLeAdvertiser
        if (advertiseCallback == null) {
            advertiseCallback = DeviceAdvertiseCallback()
            advertiser?.startAdvertising(advertiseSettings, advertiseData, advertiseCallback)
        }
}

private class DeviceAdvertiseCallback : AdvertiseCallback() {
        override fun onStartFailure(errorCode: Int) {
            super.onStartFailure(errorCode)
            val errorMessage = "failed with error: $errorCode"
           Log.i(TAG,errorMessage)
        }

        override fun onStartSuccess(settingsInEffect: AdvertiseSettings) {
            super.onStartSuccess(settingsInEffect)
            Log.d(TAG, "successfully started")
        }
}

private fun buildAdvertiseSettings(): AdvertiseSettings {
        return AdvertiseSettings.Builder()
            .setAdvertiseMode(AdvertiseSettings.ADVERTISE_MODE_LOW_POWER)
            .setTimeout(0)
            .build()
}

private fun buildAdvertiseData(): AdvertiseData {
        val dataBuilder = AdvertiseData.Builder()
            .addServiceUuid(ParcelUuid(SERVICE_UUID))
            .setIncludeDeviceName(true)
        return dataBuilder.build()
}