You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: zone.go
    path of file: ./repos/kuma/pkg/defaults
    
    the code of the file until where you have to start completion: package defaults

import (
	"context"
	"time"

	"github.com/go-logr/logr"
	"github.com/pkg/errors"
	"github.com/sethvargo/go-retry"

	"github.com/kumahq/kuma/pkg/core/resources/apis/system"
	"github.com/kumahq/kuma/pkg/core/resources/manager"
	"github.com/kumahq/kuma/pkg/core/resources/model"
	"github.com/kumahq/kuma/pkg/core/resources/store"
	"github.com/kumahq/kuma/pkg/core/runtime/component"
	"github.com/kumahq/kuma/pkg/core/user"
	kuma_log "github.com/kumahq/kuma/pkg/log"
)

type ZoneDefaultComponent struct {
	ResManager manager.ResourceManager
	Extensions context.Context
	ZoneName   string
}

var _ component.Component = &ZoneDefaultComponent{}

func (e *ZoneDefaultCom
    
func (e *ZoneDefaultComponent) Start(stop <-chan struct{}) error {
	ctx, cancelFn := context.WithCancel(user.Ctx(context.Background(), user.ControlPlane))
	defer cancelFn()
	logger := kuma_log.AddFieldsFromCtx(log, ctx, e.Extensions)
	errChan := make(chan error)
	go func() {
		errChan <- retry.Do(ctx, retry.WithMaxDuration(10*time.Minute, retry.NewConstant(5*time.Second)), func(ctx context.Context) error {
			if err := EnsureOnlyOneZoneExists(ctx, e.ResManager, e.ZoneName, logger); err != nil {
				log.V(1).Info("could not ensure that Zone exists. Retrying.", "err", err)
				return retry.RetryableError(err)
			}
			return nil
		})
	}()
	select {
	case <-stop:
		return nil
	case err := <-errChan:
		return err
	}
}