Invoices and Receipt Creation with AR_INVOICE_API_PUB and AR_RECEIPT_API_PUB + Workflow

I was working on a prototype for customer to to create the Invoices in AR and then create the CASH receipt.
End requirements are to create the Invoices and then Create the Cash receipt based on the customer number. My Customer was not interested in applying the Receipt to particular invoices, as they just want to see how much cash they have received from the customer.This requirement is related to the CHARITY Industry , and customer want to see weather people honor their commitments are Not.

In my prototype I have created a small workflow to call the Invoice  API  AR_INVOICE_API_PUB.create_invoice , Once Invoice created successfully , workflow progress to Next activity to create receipt by calling  Oracle AR_RECEIPT_API_PUB.create_cash .I have included notification to inform the user if the Invoice or receipt API fails with Expected or Unexpected error.For My testing I have also included notification for successful invoice creation.

Below is Source code for the Creation of Invoice and Receipts.

PLEASE NOTE that It was Prototype and I have added lot of hardcoding .

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Source Code
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