OAuth2 protected resources using RestTemplate

fun getSsoAccessToken(): String? {
    val restTemplate = RestTemplate()
    restTemplate.interceptors = listOf(RequestResponseLoggingInterceptor())

    val headers = HttpHeaders()
    headers.contentType = MediaType.APPLICATION_FORM_URLENCODED
    headers.accept = listOf(MediaType.APPLICATION_JSON)
    headers.setBasicAuth("<client-id>", "<client-secret>")

    val map = LinkedMultiValueMap<String, String>()
    map.add("grant_type", "password")
    map.add("scope", "openid")
    map.add("username", "<username>")
    map.add("password", "<password>")
    val request = HttpEntity<MultiValueMap<String, String>>(map, headers)
    val responseEntity = restTemplate.exchange("https://<base-url>/oauth/token", HttpMethod.POST, request, JsonNode::class.java)
    if(responseEntity.statusCode.is2xxSuccessful) {
        return responseEntity.body?.get("access_token")?.asText()
    } else {
        throw IllegalStateException("Error occurs during token generation")
    }
}

fun deleteAssessment(token: String?, id: String): String? {
    val headers = HttpHeaders()
    headers.add("Authorization", "bearer $token")
    headers.contentType = MediaType.APPLICATION_JSON
    val httpEntity = HttpEntity<String>(headers)
    val typeRef = object : ParameterizedTypeReference<ServiceResponse<JsonNode>>() {}
    val responseEntity = restTemplate.exchange("https://<base-url>/assessment/id/1", HttpMethod.DELETE, httpEntity, typeRef)
    if (responseEntity.statusCode.is2xxSuccessful) {
        println("Successfully deleted assessment: $questionnaireId")
        val response = responseEntity.body
        return response?.data?.toString()
    }
    return null
}