Retrofit2 custom interceptor that parse the response from API. After that we can check status and based on that returns a same copy that other classes can consume.

LogoutInterceptor.kt

import com.google.gson.Gson
import okhttp3.Interceptor
import okhttp3.Response
import okhttp3.ResponseBody
import org.json.JSONException


/**
 *  Logout Interceptor.
 *  Here i extend the BaseActivity to navigate user to another screen. i need runOnUIThread to execute navigateToLogin() method. 
 */
class LogoutInterceptor : BaseActivity(), Interceptor {
    
    override fun intercept(chain: Interceptor.Chain?): Response {
        val response: Response = chain?.proceed(chain.request())!!

        val globJson = response.body()!!.string()

        try {
          /**
          * GlobalResponse class is the API response model.
          * status is the class member of GlobalResponse class. we will get logout session code in status. 
          * SessionInvalid variable contains the defined status code.
          */
            val globalResponse: GlobalResponse = Gson().fromJson(globJson, GlobalResponse::class.java)
            if (globalResponse.status == SessionInvalid) {
                runOnUiThread(object : Runnable {
                    override fun run() {
                        navigateToLogin()
                      /**
                        navigateToLogin() method's body part is defined in BaseActivity. Here AppApplication is Application class
                        val intent = Intent(AppApplication.instance.applicationContext, WelcomeActivity::class.java)
                        intent.flags = Intent.FLAG_ACTIVITY_CLEAR_TASK or Intent.FLAG_ACTIVITY_NEW_TASK
                        intent.putExtra(SESSION_LOGOUT_REASON, true)
                        AppApplication.instance.startActivity(intent)
                      */
                    }
                })
            }
        } catch (e: JSONException) {
            e.printStackTrace()
        }


        // Re-create the response before returning it because body can be read only once
        return response.newBuilder()
                .body(ResponseBody.create(response.body()!!.contentType(), globJson)).build()
    }

}

OkHttpClient.kt

            /**
            * You can call your Custom interceptor while creating OkHttpClient object 
            **/
            val okHttp:OkHttpClient= OkHttpClient.Builder()
                                     .....
                                     .addNetworkInterceptor(LogoutInterceptor())
                                     ....
                                     .build()