title: Flutter | PurchaseDetails.billingClientPurchase was removed at in_app_purchase than 0.60
body: <p>There is one significant regression in the in_app_purchase 0.6.0</p>
  <p>In 0.5.2, PurchaseDetails contained the billingClientPurchase field with additional Android related information.</p>
  <p>The billingClientPurchase contained one very important piece of information: signature.</p>
  <p>This signature is required to locally verify a purchase. In 0.6.0, one can only find PurchaseDetails.verificationData.localVerificationData (another important piece of data), but no signature can be received.</p>
  <p>Please could you add the signature as well?</p>
  <pre><code>  Future&lt;bool&gt; _verifyPurchase(PurchaseDetails purchaseDetails) async
    {
      if (Platform.isAndroid) {
        try {
          final body = json.encode({
            'signature': purchaseDetails.billingClientPurchase.signature, // Compile error
            'receipt': purchaseDetails.verificationData.localVerificationData,
          })
  
          await http.post(RECEIPT_VERIFICATION_ENDPOINT_FOR_ANDROID, body: body);
  
          purchaseDetails.billingClientPurchase.isAutoRenewing; // Compile error
        } catch (e) {
          return false;
        }
      }
  
      return true;
    }
  </code></pre>