A union definition: the set of object types a value of this type may be.
Summary
Types
@type t() :: %TypedGql.Language.UnionTypeDefinition{ description: String.t() | nil, directives: [TypedGql.Language.Directive.t()], loc: map(), name: String.t() | nil, types: [TypedGql.Language.NamedType.t()] }