$orderId = $entityId;
            $order = $this->_orderRepository->get($orderId);
            if($order->canInvoice()) {

               foreach($post_data['items'] as $index => $details){
                     $quantity = $details['qty'];
             $order_item_id = $details['order_item_id'];

                     $itemsArray = [$order_item_id,$quantity];
                }
                $shippingAmount = $shipping;
                $subTotal = $subtotal;
                $grandTotal = $grandtotal;
                $taxAmount = $tax;
                $invoice = $this->_invoiceService->prepareInvoice($order, $itemsArray);
                $invoice->setShippingAmount($shippingAmount);
                $invoice->setTaxAmount($taxAmount);
                $invoice->setBaseTaxAmount($taxAmount);
                $invoice->setSubtotal($subTotal);
                $invoice->setBaseSubtotal($subTotal);
                $invoice->setGrandTotal($grandTotal);
                $invoice->setBaseGrandTotal($grandTotal);
                $invoice->setRequestedCaptureCase(MagentoSalesModelOrderInvoice::CAPTURE_ONLINE);
                $invoice->register();
                $transactionSave = $this->_transaction->addObject(
                    $invoice
                )->addObject(
                    $invoice->getOrder()
                );
                $transactionSave->save();
               // $this->invoiceSender->send($invoice);
                //send notification code
                $order->addStatusHistoryComment(
                    __('Notified customer about invoice #%1.', $invoice->getId())
                )
                ->setIsCustomerNotified(true)
                ->save();
            }
            return $invoice->getId();