Twitter API Retweet Auth Failure

Question

I'm trying to implement Twitter's Retweet API to retweet a specific tweet. But I'm having AuthFailureError while requesting that API. I'm unable to solve this issue and stuck for many days. Any help would be appreciated. Code:

private fun retweetTweet(tweetId: String) {
    val progressDialog = ProgressDialog(this)
    progressDialog.setTitle("Please wait")
    progressDialog.show()

    val jsonObject = JSONObject()
    jsonObject.put("tweet_id", "$tweetId")

    val url = "https://api.twitter.com/2/users/$userId/retweets"

    Log.d(TAG, "retweetTweet: url: $url")
    Log.d(TAG, "retweetTweet: tweet_id: $tweetId")
    Log.d(TAG, "retweetTweet: userId: $userId")

    val jsonObjReq: JsonObjectRequest =
        object : JsonObjectRequest(Method.POST, url, jsonObject, Response.Listener { response ->
            progressDialog.dismiss()
            Log.d(TAG, "retweetTweet: $response")
            try {
                Log.d(TAG, "retweetTweet: ")
            } catch (e: Exception) {
                Log.e(TAG, "retweetTweet: ", e)
            }
        }, Response.ErrorListener { error ->
            progressDialog.dismiss()
            Log.e(TAG, "retweetTweet: ", error)
        }) {

            override fun getHeaders(): MutableMap<String, String> {
                val headers: MutableMap<String, String> = HashMap()

                val auth = "${Constants.TWITTER_BARRIER_TOKEN_KEY}"
                headers["Authorization"] = auth

                return headers
            }

        }

    jsonObjReq.retryPolicy = DefaultRetryPolicy(5000, 3, 1.0f)
    Volley.newRequestQueue(this).add(jsonObjReq)

}

Screenshot Of Error: