setValue method
Writes value into the property of bean. The value must already
have the property's type (BeanWrapper converts first). Throws
StateError for a read-only property.
Implementation
void setValue(Object bean, Object? value) {
final setter = _set;
if (setter == null) {
throw StateError("Property '$name' of $T is read-only");
}
setter(bean as T, value);
}