in functions_framework_builder/lib/src/valid_json_utils.dart [80:89]
JsonReturnKind validJsonReturnType(DartType type) {
if (type.isDartAsyncFuture || type.isDartAsyncFutureOr) {
// Unwrap the future value and run again!
return _validJsonReturnTypeCore(
(type as InterfaceType).typeArguments.single,
);
}
return _validJsonReturnTypeCore(type);
}