dispose method

void dispose()

Ends connection to the BillingClient.

Consider calling dispose after you no longer need the BillingClient API to free up the resources.

After calling dispose:

Implementation

void dispose() {
  _debugAssertNotDisposed();
  _isDisposed = true;
  client.endConnection();
  _purchasesUpdatedController.close();
  _userChoiceAlternativeBillingController.close();
}