kubernetes/staging/src/k8s.io/code-generator/cmd/go-to-protobuf/protobuf/import_tracker.go

type ImportTracker …

func NewImportTracker(local types.Name, typesToAdd ...*types.Type) *ImportTracker { … }

// AddNullable ensures that support for the nullable Gogo-protobuf extension is added.
func (tracker *ImportTracker) AddNullable() { … }