Support for custom fields on printed receipts

[StefanKert]

Currently the Epson RT Printer doesn't support custom printed lines sent by the cash register. One of the things that we have added in the Digital Receipt should also be used for the Epson RT Printer to make sure that all receipt artifiacts work end 2 end.

• Extend RT Printer SCU to be able to interpret ftReceiptCaseData.cbReceiptLines array (check Digital Receipt)
• KBA for how to send custom fields / documentation?

The current digital receipt logic parses the content like this:

        var receiptLines = new List<string>();
        if (!string.IsNullOrEmpty(request.ftReceiptCaseData))
        {
            try
            {
                using var doc = JsonDocument.Parse(request.ftReceiptCaseData);
                var element = doc.RootElement;
                if (element.TryGetProperty("cbReceiptLines", out var lines))
                {
                    receiptLines = lines.EnumerateArray().Where(x => x.GetString() != null).Select(x => x.GetString()!)?.ToList() ?? new List<string>();
                }
            }
            catch { }
        }

Each row in the field cbReceiptLines contains a single line that should be printed in the footer section of the document. To esnure backwards compatibility we should support both the old format ( string based )

Example:

{
    "ReceiptRequest": {
        ....
        "ftReceiptCaseData": "{\"cbReceiptLines\":[\"Line 1\",\"Line 2\"]}",
        "ftReceiptCase": 4707387510509010945
    },

and also object based

Example:

{
    "ReceiptRequest": {
        ....
        "ftReceiptCaseData": {
                "cbReceiptLines":
                [
                        "Line 1",
                        "Line 2"
                ]
        },
        "ftReceiptCase": 4707387510509010945
    },

Sending this example would result in additional lines on the bottom of the receipt. We will currently only support adding lines to the bottom of the document.

[StefanKert]

Included in main branch. Going to release with v1.3.67