The buyer makes a payment for the goods. In this step, we define the BuyerDepositPayment transaction and related event and update the LC status:

transaction BuyerDepositPayment {
  --> LetterOfCredit lc
}

event BuyerDepositPaymentEvent {
  --> LetterOfCredit lc
}

The letter status is set to BUYER_DEBIT_PAYMENT, and the step to 7:

/**
 * buyer Deposit Payment
 * @param {org.example.lc.BuyerDepositPayment} buyerDepositPayment - buyer Deposit Payment
 * @transaction
 */
async function buyerDepositPayment(request) { // eslint-disable-line no-unused-vars
    const factory = getFactory();
    const namespace = 'org.example.lc';

    let letter = request.lc;

    if (letter.status === 'CLOSED') {
        throw new Error ('This letter of credit has already been closed');
    } else if (letter.step!== 6) {
        throw new Error ('This letter of credit should be in step 6 - DELIVERY_DOCUMENT');
    }
    letter.status = 'BUYER_DEBIT_PAYMENT';
    letter.step=7;

    const assetRegistry = await getAssetRegistry(request.lc.getFullyQualifiedType());
    await assetRegistry.update(letter);

    // emit event
    const buyerDepositPaymentEvent = factory.newEvent(namespace, 'BuyerDepositPaymentEvent');
    buyerDepositPaymentEvent.lc = letter;
    emit(buyerDepositPaymentEvent);
}