types property

List<ObjectTypeDefinition> types

http://spec.graphql.org/draft/#sel-HAHdfFDABABlG3ib:

The member types of a Union type must all be Object base types; Scalar, Interface and Union types must not be member types of a Union. Similarly, wrapping types must not be member types of a Union.

Implementation

List<ObjectTypeDefinition> get types =>
    _typeNames.map(getType).cast<ObjectTypeDefinition>().toList();