func (o *GetObjectOptions) SetUnmodified(modTime time.Time) error {
	if modTime.IsZero() {
		return ErrInvalidArgument("Modified since cannot be empty.")
	}
	o.Set("If-Unmodified-Since", modTime.Format(http.TimeFormat))
	return nil
}
SetUnmodified - set unmodified time since.
package minio
import (
	"fmt"
	"net/http"
	"time"
	"github.com/minio/minio-go/v6/pkg/encrypt"
)
type GetObjectOptions struct {
	headers              map[string]string
	ServerSideEncryption encrypt.ServerSide
}
type StatObjectOptions struct {
	GetObjectOptions
}
func (o GetObjectOptions) Header() http.Header {
	headers := make(http.Header, len(o.headers))
	for k, v := range o.headers {
		headers.Set(k, v)
	}
	if o.ServerSideEncryption != nil && o.ServerSideEncryption.Type() == encrypt.SSEC {
		o.ServerSideEncryption.Marshal(headers)
	}
	return headers
}
func (o *GetObjectOptions) Set(key, value string) {
	if o.headers == nil {
		o.headers = make(map[string]string)
	}
	o.headers[http.CanonicalHeaderKey(key)] = value
}
func (o *GetObjectOptions) SetMatchETag(etag string) error {
	if etag == "" {
		return ErrInvalidArgument("ETag cannot be empty.")
	}
	o.Set("If-Match", "\""+etag+"\"")
	return nil
}
func (o *GetObjectOptions) SetMatchETagExcept(etag string) error {
	if etag == "" {
		return ErrInvalidArgument("ETag cannot be empty.")
	}
	o.Set("If-None-Match", "\""+etag+"\"")
	return nil
}