def _get_referenced_type_equivalences(graphql_types, type_equivalence_hints):
    """Filter union types with no edges from the type equivalence hints dict."""
    referenced_types = set()
    for graphql_type in graphql_types.values():
        if isinstance(graphql_type, (GraphQLObjectType, GraphQLInterfaceType)):
            for _, field in graphql_type.fields.items():
                if isinstance(field.type, GraphQLList):
                    referenced_types.add(field.type.of_type.name)
    return {
        original: union
        for original, union in type_equivalence_hints.items()
        if union.name in referenced_types
    }
Filter union types with no edges from the type equivalence hints dict.