'void com.vimeo.networking.GsonDeserializer.deserialize

java.lang.NullPointerException: Attempt to invoke virtual method 'void com.vimeo.networking.GsonDeserializer.deserialize(com.google.gson.Gson, java.lang.Object, com.vimeo.networking.callbacks.ModelCallback)' on a null object reference
        at com.vimeo.networking.VimeoClient$5.success(VimeoClient.java:1169)
        at com.vimeo.networking.callbacks.VimeoCallback.onResponse(VimeoCallback.java:55)
        at retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall$1$1.run(ExecutorCallAdapterFactory.java:70)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:201)
        at android.app.ActivityThread.main(ActivityThread.java:6810)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)

var configBuilder = Configuration.Builder(VimeoHelper.clientId, VimeoHelper.clientSecret, VimeoHelper.SCOPE)
    .setCacheDirectory(activity?.getCacheDir())


VimeoClient.initialize(configBuilder.build());
VimeoClient.getInstance().authorizeWithClientCredentialsGrant(object : AuthCallback {
    override fun success() {
        vimeoClient = VimeoClient.getInstance();
        playVideo();
    }

    override fun failure(error: VimeoError?) {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }
})


vimeoClient ?.fetchNetworkContent("/videos/354539932", object : ModelCallback<VideoList>(com.vimeo.networking.model.VideoList::class.java) {
    override fun success(video: com.vimeo.networking.model.VideoList?) {
        Helper.setLog(TAG,"success")
    }

    override fun failure(error: VimeoError) {
        Helper.setLog(TAG,"failure"+error.developerMessage)
    }
})

Start in VimeoClient.java around line 1169 and trace the GsonDeserializer reference through VimeoCallback.java and the reported callback path. Identify why the deserializer is null for this request, then verify that the same fetch invokes the success or failure callback without a NullPointerException.