Custom Labels Handling Problem

[DiagonalArg]

Checklist

• I can reproduce the bug with the latest version given here.
• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• I have taken the time to fill in all the required details. I understand that the bug report will be dismissed otherwise.
• This issue contains only one bug.
• I have read and understood the contribution guidelines.

Affected app version

1.1.0

Affected Android/Custom ROM version

GrapheneOS

Affected device model

Pixel 7

How did you install the app?

GitHub releases

Steps to reproduce the bug

Create a vCard with custom labels like:

Cell First, Last
"Something; Tricky"

The labels are shown correctly in the app. They are also shown correctly in Stock.

Sharing the card from Stock to a text editor generates a vCard with no labels:

BEGIN:VCARD
VERSION:2.1
N:Last;First;Middle;;
FN:First Middle Last
TEL;:555-1212
TEL;:666-2323
NOTE:Some notes...
END:VCARD

Sharing the card from Fossify produces an error:

Error:
java.lang.illegalArgumentException: Pr...

Selecting a text editor anyway, produces an empty card.

Expected behavior

No error and a valid vCard.

Actual behavior

Error and empty vCard

Screenshots/Screen recordings

Additional information

The error appears to be caused by the quotation marks in the label for the number 666-2323. Removing those, I am able to export from Fossify as:

BEGIN:VCARD
VERSION:3.0
PRODID:ez-vcard 0.11.3
FN:First Middle Last
N:Last;First;Middle
TEL;TYPE="Cell First, Last":555-1212
TEL;TYPE="Something; Tricky":666-2323
NOTE:Some notes...
END:VCARD

I see that the spec doesn't seem to offer a means of quoting a double quote:

param-value = *SAFE-CHAR / DQUOTE *QSAFE-CHAR DQUOTE

   any-param  = (iana-token / x-name) "=" param-value *("," param-value)

   NON-ASCII = UTF8-2 / UTF8-3 / UTF8-4
     ; UTF8-{2,3,4} are defined in [[RFC3629](https://datatracker.ietf.org/doc/html/rfc3629)]

   QSAFE-CHAR = WSP / "!" / %x23-7E / NON-ASCII
     ; Any character except CTLs, DQUOTE

   SAFE-CHAR = WSP / "!" / %x23-39 / %x3C-7E / NON-ASCII
     ; Any character except CTLs, DQUOTE, ";", ":"

So unless you want to introduce '\"', in a way analogous to the use of '\;' in ORG:Company\;Department , then perhaps there should be a softer failure mode?

Question

What is the internal representation of contacts that allows "Something; Tricky" to be displayed, but not exported?

Also, other questions about the behavior, here.