func (s *RefreshService) Index(index ...string) *RefreshService {
	s.index = append(s.index, index...)
	return s
}
Index specifies the indices to refresh.
package elastic
import (
	"context"
	"fmt"
	"net/url"
	"strings"
	"github.com/olivere/elastic/uritemplates"
)
type RefreshService struct {
	client *Client
	index  []string
	pretty bool
}
func NewRefreshService(client *Client) *RefreshService {
	builder := &RefreshService{
		client: client,
	}
	return builder
}