Memory leak in startactivityforresult

If we have to start Activity B in Activity A for result as follow 

We will call startActivityForResult from Activity A we will set some result in out activity B and return result.

But what if user presses back button on Activity B how should we handle this case.

I was running LeakCanary and found surprising result that it was always leaking my Activity B. reason is that it wasn't finishing and staying in memory even after returning to Activity B with Back Press.

So here is the solution that I found to resolve this. So quick fix is call method finishActivity with request code that you have passed while calling activity B. 

class ActivityA: AppCompatActivity(){

    private val requestCode = 1001

    fun startActivityB(){

    startActivityForResult(Intent(this, ActivityB::class.java).apply 

                {

                    putExtra("category_id", currentCategory._id)

                    putExtra("category_color", currentCategory.color)

                    putExtra("category_name", currentCategory.name)

                }, requestCode)

    }

    override fun onActivityReenter(resultCode: Int, data: Intent?) {

        super.onActivityReenter(resultCode, data)

        finishActivity(requestCode)

    }

}