hash method
The mapping method to calculate the hash of value.
Implementation
@override
int hash(T value, MappingContext context) {
  return Object.hashAll(
    _members.map((f) {
      return context.container.hash(f.get(value));
    }),
  );
}The mapping method to calculate the hash of value.
@override
int hash(T value, MappingContext context) {
  return Object.hashAll(
    _members.map((f) {
      return context.container.hash(f.get(value));
    }),
  );
}