const google.golang.org/protobuf/reflect/protoreflect.Optional

9 uses

	google.golang.org/protobuf/reflect/protoreflect (current package)
		proto.go#L204: 	Optional Cardinality = 1 // appears zero or one times
		proto.go#L212: 	case Optional, Required, Repeated:
		proto.go#L222: 	case Optional:
		proto.go#L236: 	case Optional:

	google.golang.org/protobuf/encoding/protojson
		encode.go#L183: 	fd.L1.Cardinality = protoreflect.Optional

	google.golang.org/protobuf/internal/encoding/tag
		tag.go#L48: 			f.L1.Cardinality = protoreflect.Optional
		tag.go#L160: 	case protoreflect.Optional:

	google.golang.org/protobuf/internal/filedesc
		desc.go#L357: 	return (fd.L0.ParentFile.L1.Syntax == protoreflect.Proto2 && fd.L1.Cardinality == protoreflect.Optional && fd.L1.ContainingOneof == nil) || fd.L1.IsProto3Optional
		desc.go#L468: 	return (xd.L0.ParentFile.L1.Syntax == protoreflect.Proto2 && xd.L1.Cardinality == protoreflect.Optional) || xd.lazyInit().IsProto3Optional