Webhooks JSON Definitions

Every webhook request contains the following two objects in the payload:

  • event Contains metadata about the event.
  • sender Contains the details of the workplace that is sending the event.

Most webhooks, with the exception of a few like backgroundPoll, also contain the following object:

  • session Contains the details of the current session.

Then there are some objects that only occur with specific webhook events:

  • scanCode (only occurs with scanCode event)
    Contains the scanned code’s details.
  • addSessionLine (only occurs with addSessionLine event)
    Contains the added line’s details.
  • removeSessionLine (only occurs with removeSessionLine event)
    Contains the removed line’s details.
  • mergeSession (only occurs with mergeSession event)
    Contains the ID of the session that the current session is merging with.
  • completeSession (only occurs with completeSession event)
    Contains the payment details of the session.
  • selectRelation (only occurs with selectRelation event)
    Contains the selected relation details.
  • printBill (only occurs with printBill event)
    Contains the details of previous payments to the bill.
  • customAction (only occurs with customAction event)
    Contains the details of the custom action.
  • course (only occurs with kitchen...Course event)
    Contains the details of the underlying course.
  • externalPayment (only occurs with ...ExternalPayment event)
    Contains the external payment’s details.
  • cafeteriaOrder
    Contains the details of the underlying cafeteria order.
  • tableOrder
    Contains the details of the underlying table order.
  • order
    Contains the details of the underlying order.
  • table
    Contains the details of the underlying table.

Finally, some objects may only occur in certain circumstances.

  • dialog (only occurs after a dialog response)
    Contains selected dialog options.
  • form (only occurs after a form response)
    Contains submitted form values.
  • openUrl (only occurs when the client supports it)
    Contains preferences regarding usage of the openUrl response.

There is also always the possibility that your reply triggers an error, this will cause the following request to be sent to you:

  • error
    Signify an error in the response that was sent.

When replying to a webhook, you can choose to reply with an empty body, or with one or more of the following objects:

  • error
    Signify an error in the request that was sent.
  • scanCode (only works with scanCode)
    Response to the scanCode event.
  • lineChanges
    Request changes to the session’s lines.
  • lineAdditions
    Request additions to the session’s lines.
  • lineDeletions
    Request deletions from the session’s lines.
  • lockSession
    Lock the session from further changes.
  • lockSessionForAdditions
    Lock the session from further additions (deletions/decreases is allowed).
  • receiptFooter (only works with completeSession)
    Request some extra data to be printed on the footer of the receipt.
  • billFooter (only works with printBill)
    Request some extra data to be printed on the footer of the bill.
  • dialog
    Request a dialog to show up on screen.
  • form
    Request a form with various input fields to show up on screen.
  • message
    Request messages to show up on the user screen and/or the customer screen.
  • requestScanCode
    Request a code to be scanned in the POS.
  • displayBarcode
    Display a code on the POS customer display.
  • hideBarcode
    Instantly hide a code that is currently displayed.
  • openUrl
    Display or redirect to a website
  • customActionChange
    Change the caption of a customAction button.
  • vatMethodChange
    Change the VAT method of the current session.
  • externalCardScan
    Notify the POS that an external card was scanned, that the POS should know about.
  • prepayTable
    Register payment on a table.
  • requestCustomAction
    Request the POS to execute a specific custom action.
  • version
    A string that represent the version of your external software (or webhook middleware).
  • externalPayment (only works with ...ExternalPayment)
    Influence the currently running external payment.

When you receive a polling webhook (you can recognize this by the property event.eventPolling), you must reply with at least a polling object in the response. Otherwise, MplusKASSA will continue querying your endpoint until the webhook is manually cancelled.

  • polling Tell MplusKASSA to continue polling or not, and optionally display some messages.

Request objects

event

Property Type Explanation
event.eventBlocking boolean Is the event blocking? When this is true, MplusKASSA is waiting for your response.
event.eventPolling boolean Is the event polling? When this is true, MplusKASSA will continue to query your endpoint until you respond that polling is finished (see polling response).
event.eventCounter int An increasing counter that helps you check if you already processed an event. Please note that the counter may occasionally reset.
event.eventTimestamp datetime The date and time that the event occurred.

sender

Property Type Explanation
branchNumber int The branch the event was sent from.
workplaceNumber int The workplace the event was sent from.
instanceId uuid Every time the POS is restarted, this UUID is regenerated.
paymentStarted boolean When the POS is in the payment screen, this variable will be true. To detect changes to and from the payment screen, you can listen to the startPayment and cancelPayment events.
productName string Whether the webhooks are triggered from the Desktop POS MplusQ or through the API MplusQservice.

Browser details have been added in v48.0.0

When webhooks are triggered through one of our web apps, this will contain information about the browser that was used.
browserFamily string (optional) The browser used.
browserVersion string (optional) The version of the browser used.
deviceType string Mobile, Tablet, Desktop, or Bot
platformFamily string (optional) The platform (or OS) used.
platformVersion string (optional) The version of the platform used.

hasReceiptPrinter was added in v57.0.0

hasReceiptPrinter boolean (optional) Whether the workplace has a receipt printer configured.

Receipt printer details may be added in a future version

overallState string (optional) Offline, NotReady, or Ready
coverState string (optional) Unknown, Open, or Closed
paperState string (optional) Unknown, Empty, Low, or Present
ageInSeconds int (optional) How many seconds ago the state was last updated.

session

Property Type Explanation
session.sessionId uuid The session’s unique ID.
session.table.number bigint (optional) The table number that the session is attached to.
session.table.subNumber bigint (optional) The table sub number that the session is placed upon.
session.lines array The session’s lines.
session.lines[].lineId uuid The line’s unique ID.
session.lines[].articleNumber bigint (optional) The line’s article number.
session.lines[].priceIncl number (optional) The line’s price including VAT.
session.lines[].quantity number (optional) The line’s quantity.
session.lines[].text string The line’s textual description.
session.lines[].discountPercentage number (optional) The line’s percentual discount, this stacks with the discount amount.
session.lines[].discountAmount number (optional) The line’s discount amount, this stacks with the discount percentage.
session.lines[].supplierArticleNumber string (optional) Article number from the supplier, if available.
session.lines[].pluNumber string (optional) PLU number, if available.
session.lines[].extArticleId string (optional) External article ID, if available.
Note that you would normally not be able to have a line with a discount from MplusKASSA and an external discount. It can only be one or the other.
session.lines[].externalDiscount.discountId uuid (optional) This is a UUID you generate and store to remember that you applied this discount.
session.lines[].externalDiscount.discountDescription string (optional) A textual description for the external discount.
session.lines[].externalDiscount.discountPercentage number (optional) The line’s external percentual discount, this stacks with the external discount amount.
session.lines[].externalDiscount.discountAmount number (optional) The line’s external discount amount, this stacks with the external discount percentage.
Note that you would normally not be able to have a line with a discount from MplusKASSA and an external discount. It can only be one or the other.
session.payments[] payment (optional) The session’s payments, including any prepayments that were made at any point in its history.
Look at the completeSession object for a description of the payment’s properties.

scanCode

Property Type Explanation
scanCode.scannedCode string A textual representation of the code that was scanned.
scanCode.codeType string barcode, rfid

addSessionLine

Property Type Explanation
addSessionLine.line.lineId string The added line’s unique ID.<
addSessionLine.line.articleNumber bigint (optional) The added line’s article number.
addSessionLine.line.priceIncl number (optional) The added line’s price including VAT.
addSessionLine.line.quantity number (optional) The added line’s quantity.
addSessionLine.line.text string The added line’s textual description.
On top of this the added line can also contain all the additional properties a session.lines[] object can contain.

removeSessionLine

Property Type Explanation
removeSessionLine.line.lineId string The removed line’s unique ID.
removeSessionLine.line.articleNumber bigint (optional) The removed line’s article number.
removeSessionLine.line.priceIncl number (optional) The removed line’s price including VAT.
removeSessionLine.line.quantity number (optional) The removed line’s quantity.
removeSessionLine.line.text string The removed line’s textual description.
On top of this the added line can also contain all the additional properties a session.lines[] object can contain.

mergeSession

Property Type Explanation
mergeSession.mergeWithSessionId string The session that the current session is merged with.
session.sessionId string The session that is merged.

completeSession

Property Type Explanation
completeSession.payments[].amount number The amount that was paid with this specific payment method.
completeSession.payments[].description string The description label of this payment method.
completeSession.payments[].method string The reference id of this payment method.
The completeSession.payments list only contains the payments that were made in the final transaction, and does not include any previous prepayments that were made to the session. You can find a list of all (pre)payments in the session.payments list.

selectRelation

Added in MplusKASSA v43.1.1

Check the definition of session for possible contents of relation.

When a relation is deselected, the value of relation will be null.

customAction

Property Type Explanation
customAction.customActionId text The manually configured ID of the customAction button that was clicked.
customAction.buttonCaption text The manually configured caption of the customAction button that was clicked, can be changed through a webhook response.
customAction.onStartup boolean Whether or not the webhook was called during POS startup. You may use this to set initial state.
customAction.longClick boolean (optional) Whether or not the button was held for a long time. You may decide to alternate behaviour based on this.
customAction.numpadValue number (optional) The current value of the POS numpad input.

course

Property Type Explanation
customAction.customActionId text The manually configured ID of the customAction button that was clicked.
customAction.numpadValue number (optional) The current value of the POS numpad input.

externalPayment

Property Type Explanation
externalPaymentId string Each external payment receives a new id.
amount number The amount that has to be paid.
method string The name of the payment method that was configured to trigger the webhook.
callbackUrl string (optional) If this URL is provided, please call it when you have the final status of the external payment. This is an important step in speeding up certain parts of the payment processing. You don’t need to do anything with the result of this request.

callbackUrl has been added in v56.0.0

cafeteriaOrder

Property Type Explanation

tableOrder

Property Type Explanation

order

Property Type Explanation

table

Property Type Explanation

dialog

When you reply with a dialog, the user will be able to select some dialog options. Afterwards, the same event will be sent to you again, but this time including the selected dialog options.

Property Type Explanation
dialog.selectedDialogOptionIds int[] The ID’s of the selected dialog option. Can be zero, one or more.
On top of this, you also receive all the original data from the event.

form

Added in MplusKASSA v59

When you reply with a form, the user will be able to fill out and submit it. Afterwards, the same event will be sent to you again, but this time including the submitted form values.

Property Type Explanation
form.id string Form identifier as specified in the initial form response.
form.cancelled boolean (optional) If the form was explicitly cancelled, this will be true.
form.fields[].id string Field identifier as specified in the initial form response.
form.fields[].value string No matter the original field type, submitted values are always sent as string.
form.fields[].selected string[] Contains the selected options in case of a select field.
On top of this, you also receive all the original data from the event.

openUrl

Added in MplusKASSA v48.0.0

Contains preferences regarding usage of the openUrl response.

Property Type Explanation
redirectUrl string If you plan to redirect the client to another URL during webhook interaction, please redirect back to this URL after completion.

error

Property Type Explanation
error.code string One of the Error Codes.
error.message string Additional descriptive explanation of the cause of the error.
original object All of the details of the original event.

Response objects

error

Property Type Explanation
error.code string One of the Error Codes.
error.message string Additional descriptive explanation of the cause of the error.

scanCode

Property Type Explanation
scanCode.recognized boolean Did you recognize the code or not? If you respond with true, the POS will stop looking for the code in its own data.
scanCode.relationNumber int (optional) A relation to select in the POS.

lineChanges

Property Type Explanation
lineChanges[].lineId uuid The UUID of the session line that you want to change.
lineChanges[].externalDiscount externalDiscount (optional) The details of an external discount are explained below.
externalDiscount.discountId uuid This is a UUID you
generate and store to remember that you applied this discount.
externalDiscount.discountPercentage number (optional) The discount percentage that you want to apply to the line.
externalDiscount.applyToQuantity number (optional) The quantity of this line that you want to apply the discount too. For example, if the quantity of the line is 2, but you want to apply the discount to 1 of these 2.
externalDiscount.discountAmount number (optional) The exact amount
of discount percentage that you want to apply to the line.
externalDiscount.discountDescription string (optional) A descriptive label for the discount.
externalDiscount.discountType string (optional) Can be any kind of text, will be usable as a filter in reports

lineAdditions

Property Type Explanation
lineAdditions[].lineId uuid (optional) The UUID of the session line that you want to add. You are allowed to generate this. If you omit this an UUID will be generated automatically, but it will be more difficult for you to know which line you added.
lineAdditions[].articleNumber bigint (optional) This number should be present in the MplusKASSA administration.
lineAdditions[].barcode string (optional) This barcode should be present in the MplusKASSA administration.
lineAdditions[].pluNumber string (optional) This PLU number should be present in the MplusKASSA administration.
lineAdditions[].supplierArticleNumber string (optional) This supplier article number should be present in the MplusKASSA administration.
lineAdditions[].extArticleId string (optional) This external article ID should be present in the MplusKASSA administration.
You can add an article through articleNumber, barcode, pluNumber, supplierArticleNumber, extArticleId, or a combination thereof.
lineAdditions[].priceIncl number (optional)
The line’s price including VAT. If you omit this, the default price will be used.
lineAdditions[].quantity number (optional) The line’s quantity (how many). If you omit this, a default quantity of 1 will be used.
lineAdditions[].text string (optional) The line’s text (description). If you omit this, the default article text will be used.
You can add a simple text line (without any article references) by using only text.
lineAdditions[].externalDiscount externalDiscount (optional) See the explanation at session for more details.

lineDeletions

Property Type Explanation
lineDeletions[].lineId uuid The UUID of the session line that you want to delete.
It is possible that your request for deletion will be denied. For example, you can only delete lines that you yourself added. You will receive an error message if this is the case.

Since v11.3.0 this behaviour depends on the setting “Webhooks mogen alle regels verwijderen”.

lockSession

Added in MplusKASSA v11.1.0

Property Type Explanation
lockSession boolean Locks or unlocks the session from further changes.

lockSessionForAdditions

Added in MplusKASSA v16.2.0

Property Type Explanation
lockSessionForAdditions boolean Locks or unlocks the session from further additions (deletions/decreases are allowed).

receiptFooter

Attention: receiptFooter only works with the completeSession event.

Or for multiple footers, use an array:

Property Type Explanation
textBefore string (optional) The additional text that you want to print on the receipt footer before the code. New lines ( \n) are supported.

textBeforeOptions was added in v59

textBeforeOptions.align string (optional) Available alignments are: left (default), center and right.
textBeforeOptions.doubleHeight boolean (optional) Indicate whether the line should have double the normal character height.
textBeforeOptions.doubleWidth boolean (optional) Indicate whether the line should have double the normal character width.
textBeforeOptions.underline boolean (optional) Indicate whether the line should get underlined.
textBeforeOptions.bold boolean (optional) Indicate whether the line should be bold.
barcode.codeType string (optional) The type of barcode you want to print on the receipt footer. Available types are: code128 (default) or qrcode.
barcode.code string (optional) The code that you want to be printed as a barcode on the receipt footer.
textAfter string (optional) The additional text that you want to print on the receipt footer after the code. New lines ( \n) are supported.

textAfterOptions was added in v59

textAfterOptions (optional) See textBeforeOptions above for a full explanation.
printSeparate boolean (optional) Set to true if the footer should be printed separately from the receipt. (The receipt printer will make a cut between the receipt and this footer.)
It is possible that your request for extra data on the footer will be denied. You will receive an error message if this is the case, and the receipt will be printed without
your additional data.

If you do not see the receipt footer text and/or code appear on the printed receipt, it is possible that the receipt layout is not properly configured. Please contact our support at dev@mpluskassa.nl so we can help you resolve this issue.

billFooter

Added in MplusKASSA v16.2.0

Attention: billFooter only works with the printBill event.

The JSON details of billFooter are identical to receiptFooter.

dialog

Property Type Explanation
dialog.required boolean Is a choice required?
dialog.allowMultipleOptions boolean Is more than one choice allowed?
dialog.dialogTitle string Which title should the dialog show?
dialog.columns int (optional) How many columns should the dialog use to display the options?
dialog.dialogOptions[].optionId int The option’s ID.
dialog.dialogOptions[].optionName string The option’s textual description.
dialog.dialogOptions[].optionColor string The option’s color in hexadecimal format.

requireConfirmation was added in v46

dialog.requireConfirmation boolean (optional) Do you need to click confirm after selecting an option? Useful to prevent misclicks.

articleNumber, barcode, pluNumber, supplierArticleNumber, extArticleId were added in v59

dialogOptions[].articleNumber string (optional) Will enrich the option button with article information and imagery from the POS system.
dialogOptions[].barcode
dialogOptions[].pluNumber
dialogOptions[].supplierArticleNumber
dialogOptions[].extArticleId

form

Added in MplusKASSA v59

Property Type Explanation
form.id string Form identifier that will be included when the form is submitted.
form.title string Title will be displayed above the form.
form.enableReset boolean (optional) Whether to display the button that will reset the form to its original state.
form.fields[].id string Field identifier that will be included when the form is submitted.
form.fields[].type string text, email, number, select, date, time, checkbox, label
form.fields[].required boolean Whether the field is required.
form.fields[].separator string (optional) none, above, below
form.fields[].label string What caption to display with the form field.
form.fields[].hint string (optional) A longer explanation to clarify the requirements.
form.fields[].value string (optional) A default value to populate the field with.
form.fields[].minimumLength int (optional) A minimum required text length.
form.fields[].maximumLength int (optional) A minimum required text length.
form.fields[].regex string (optional) A regex pattern to validate the input.
form.fields[].decimals int (optional) How many decimals to allow on a number field.
form.fields[].miminumValue number (optional) Minimum value of a number field.
form.fields[].maximumValue number (optional) Maximum value of a number field.
form.fields[].multiple boolean (optional) Whether to allow multiple selections on a select field.
form.fields[].columns boolean (optional) How many columns to use to display the select options.
fields[].options[].id string Option identifier that will be included when the form is submitted.
fields[].options[].label string The label that will be display on the option.
fields[].options[].color string (optional) Preset color name or hex code that will be used as background color.
fields[].options[].selected boolean (optional) Whether the option should already be selected.
fields[].options[].image string (optional) This image will be shown on the option.

image was added in v59.3.2

fields[].options[].articleNumber string (optional) Will enrich the option button with article information and imagery from the POS system.
fields[].options[].barcode
fields[].options[].pluNumber
fields[].options[].supplierArticleNumber
fields[].options[].extArticleId
fields[].options[].disabled boolean (optional) Can be used to show an option that is not selectable.

disabled was added in v59.3.2

message

Please note that the message property is an array that allows for multiple messages to be returned in a single reply.
Property Type Explanation
message[].message text (optional) Show a message on the POS user’s display..
message[].customerMessage text (optional) Show a message on the POS customer display.
message[].displayTime int (optional) This will ensure the message and customerMessage are shown for at least this amount of seconds.
message[].messageDisplayTime int (optional) This will ensure the message is shown for at least this amount of seconds.
message[].customerMessageDisplayTime int (optional) This will ensure the customerMessage is shown for at most this amount of seconds.
message[].hideTimestamp boolean (optional) When set to true, this will hide the timestamps that are usually shown in front of the messages.
message[].clearScreen boolean (optional) When set to true, this will clear all previous messages.
message[].clearCustomerScreen boolean (optional) When set to true, this will clear the current customer message.
message[].monospacedFont boolean (optional) When set to true, this will display the messages in a monospaced font so you can better align multiple lines.
message[].backgroundColor string (optional) The background color of the message popup in hexadecimal format. Or preset color names, like “red” and “green”.

requestScanCode

Added in MplusKASSA v13.1.0

Property Type Explanation
requestScanCode.required boolean Is a scan required?
requestScanCode.requestTitle boolean What would you like the POS screen to display to the user?

displayBarcode

Added in MplusKASSA v21.2.0

Property Type Explanation
displayBarcode.codeType string barcode, rfid, qrcode
displayBarcode.code string The contents of the barcode

hideBarcode

Added in MplusKASSA v21.2.0

Property Type Explanation
hideBarcode boolean Instantly hide a code that is currently displayed.

openUrl

Added in MplusKASSA v48.0.0

Property Type Explanation
url text The actual URL to open.
autoOpen boolean (optional) Whether or not to automatically open the URL.
urlTitle text (optional) The title of the link/button in case the URL is not set to open automatically, or is unable to open automatically.
closeOnDomainChange boolean (optional) Set this if you want the browser component to automatically close when the current domain changes, e.g. from payment-platform.example.com to some-other-domain.com.
minimumWidth int (optional) In case of a browser popup, determines the minimum width the popup should receive.
minimumHeight int (optional) In case of a browser popup, determines the minimum height the popup should receive.

polling

Added in MplusKASSA v11.3.0

Property Type Explanation
polling.finished boolean Tell MplusKASSA whether the polling process is finished or not. When you return false, MplusKASSA will immediately resend the request to your endpoint.
polling.message text (optional) Show a message on the POS user’s display. Use this to update the user on progress made in the polling process.
polling.customerMessage text (optional) Show a message on the POS customer display. Use this to update the customer on progress made in the polling process.
polling.displayTime int (optional) This will ensure the message and customerMessage are shown for at least this amount of seconds.
polling.messageDisplayTime int (optional) This will ensure the message is shown for at least this amount of seconds.
polling.customerMessageDisplayTime int (optional) This will ensure the customerMessage is shown for at most this amount of seconds.
polling.hideTimestamp boolean (optional) When set to true, this will hide the timestamps that are usually shown in front of the messages.
polling.clearScreen boolean (optional) When set to true, this will clear all previous messages.
polling.clearCustomerScreen boolean (optional) When set to true, this will clear the current customer message.
polling.monospacedFont boolean (optional) When set to true, this will display the messages in a monospaced font so you can better align multiple lines.

customActionChange

Added in MplusKASSA v15.1.0

Property Type Explanation
customActionChange.customActionId text The ID of the customAction button that should be changed.
customActionChange.buttonCaption text The desired new caption for the customAction button.

vatMethodChange

Added in MplusKASSA v15.1.0

Property Type Explanation
vatMethodChange text inclusive, exclusive, shifted

externalCardScan

Notify the POS that an external card was scanned, that the POS should know about.

Added in MplusKASSA v16.2.0

Property Type Explanation
externalCardScan.cardIdentifier text (optional) Use any kind of string that you use as identifier for this card within your system. Does not need to be present within the POS.
externalCardScan.cardDescription text (optional) Enter the name of the card owner, or a description of the card itself.
externalCardScan.cardBalance number (optional) The card’s current balance.
externalCardScan.cardExpiration datetime (optional) The date and time when the card expires and is no longer usable. Please note that we do not actually do anything with this date, it is only used for informational purposes in the POS.
externalCardScan.cardBlocked boolean (optional) When set to true the POS will indicate on screen that the card is blocked.
externalCardScan.displayTime int (optional) You can use this to influence the time until the card details should be hidden again. This overrides the setting in the POS itself. Set to 0 to keep the details on screen until the next receipt.
externalCardScan.isNewBalance boolean (optional) When set to true the POS will interpret the balance card as being the balance after the transaction and display accordingly.
Even though all properties are optional, nothing will be displayed on the POS if you omit them all.

prepayTable

Added in MplusKASSA v16.2.0

Property Type Explanation
prepayTable.table.number int Designate the table’s number that the payments are meant for.
prepayTable.table.subNumber int (optional) Designate the table’s subnumber that the payments are meant for.
prepayTable.sessionId uuid Provide the session ID of the table.
prepayTable.payments[].paymentId uuid Provide a unique ID, the POS will use to make sure this payment is not registered more than once.
prepayTable.payments[].amount number The amount that was paid.
prepayTable.payments[].method text (optional) The method that you want to register this payment to. If omitted, the POS uses the generic WEBHOOK payment method.

requestCustomAction

Added in MplusKASSA v17.0.0

Property Type Explanation
requestCustomAction.customActionId text The manually configured ID of the customAction button that you would like to trigger.
It is important to realize that this is a request to trigger the custom action, not a guarantee that it will. Reasons why the custom action may not trigger are: (1) the POS is not running, (2) the POS is currently in an interrupted state (like processing an electronic payment), (3) the POS currently has no logged in user or (4) the POS is currently in a blocked state (like displaying a dialog).

version

Added in MplusKASSA v23.0.0

Property Type Explanation
version text A string representing the version of your software (or the version of the Webhook middleware you created).
This version number will be added to the communication log and can help with debugging version-related problems.

externalPayment

Influence the currently running external payment.

Property Type Explanation
externalPaymentId uuid The external payment ID as received from the POS in the first place. So the POS can verify you are talking about the same payment.
started boolean (optional) Has the external payment process been started? The external payment flow won’t progress from the start, to poll stage until you respond TRUE.
confirmed boolean (optional) Has the external payment process been succesfully completed? The payment flow will end and the payment will be registered after you respond TRUE to this.
cancelled boolean (optional) Has the external payment process been cancelled/aborted/failed? The payment flow will end and the payment will be not be registered after you respond TRUE to this.
finalAmount number (optional) When the external payment succeeds, but with a differing amount than requested, you can specify the actual final amount through this variable. This requires activation of the software setting Webhooks > Algemeen > Webhooks mogen het via hen betaalde bedrag aanpassen.

Added in MplusKASSA v48.0.0

externalTransactionReference string (optional) Use this to assign a reference to the external transaction, which will be stored with the POS payment..
receiptTexts[].type string (optional) cardholder (default), merchant. Use this to tell the POS for whom the receipt is intended.
receiptTexts[].text string The actual text to print on the receipt.
receiptTexts[].requiresSignature boolean (optional) When this is true, the POS will prompt the merchant to have the cardholder sign this receipt.
cardType string (optional) Use this to store the used card type with the payment, e.g. Maestro or VPAY. This may be used by the POS to group payments..
terminalId string (optional) Use this to store a terminal ID with the payment, which may be used by the POS to group payments..
method string (optional) Use this to store which payment method was used externally.
requiresReceiptPrinter boolean (optional) Use this in the startExternalPayment response to let us know a configured printer is a requirement for a successful transaction.
For an explanation of all the remaining message-related properties, please see message.