Gracefully handle unsupported enum values

[via-guy]

Currently when an unsupported enum value is found the decoder throws an ArgumentError. This can completely break an app in production when an enum value is added to the server.

Currently the only option is to add an xUnknown value to each enum, which seems completely unnecessary for a nullable value.

It would be great to either add a new property to JsonKey, e.g. allowUnsupportedEnumValue, or handle the same logic if both nullable == true and unknownEnumValue == null.

Flutter 1.22.6 • channel stable • https://github.com/flutter/flutter.git
Framework • revision 9b2d32b605 (8 weeks ago) • 2021-01-22 14:36:39 -0800
Engine • revision 2f0af37152
Tools • Dart 2.10.5

[jeiea]

Is it a duplicate of #559?

[via-guy]

@jeiea I guess it is.

[kevmoo]

Duplicate of #559