flagBuilder property
Builds the country-flag visual for an ISO 3166-1 alpha-2 code.
Lets host apps override how BankCountryFlag (and therefore every
flag-bearing widget: country picker, phone field, address card,
travel notice) renders flags — e.g. to plug in bundled flag artwork,
an SVG set, or a CDN-backed image. The returned widget is laid out
inside a box of exactly Size, so builders should fill it (e.g. with
BoxFit.cover). When null, BankCountryFlag falls back to its
built-in rendering (a crafted ISO-code chip by default).
Implementation
final Widget Function(BuildContext context, String isoCode, Size size)?
flagBuilder;