Bundle buyIntentBundle = inappService.getBuyIntent(3, this.getPackageName(), \"android.test.purchased\", \"inapp\", \"myUserId\");
int responseCode = buyIntentBundle
As per @MarsPeople said on comment It's because of google play store's new update (version 8.0.26.R-all [0] [PR] 161173660). I tested(in app billing) around 3-4 device which contain this google play store version so in that device google play store crash and get nullpointer exception, but When I uninstall the update and test it with older version (like in my case version 5.1.11) it work perfectly but after some time play store update forcefully (version 8.0.26.R-all [0] [PR] 161173660) and then I tried it then google play store crash. So yes we have to wait until google give new update on this issue :)
but surprisingly it work perfectly with real SKU which is provided from google console. and not work with test SKU (android.test.purchased)
I hope this will help someone who get this issue on google play store version 8.0.26.R-all [0] [PR] 161173660