sample.go

type Payload struct {
	ID     string `json:"Id"`
	Title  string `json:"title"`
	Type   string `json:"type"`
	Fields Fields `json:"fields"`
}

type Fields struct {
	FixVersion []FixVersion `json:"fixVersions"`
}

type FixVersion struct {
	Self      string `json:"self"`
	ID        string `json:"id"`
	Name      string `json:"name"`
	Archived  bool   `json:"archived"`
	Released  bool   `json:"released"`
	ProjectID int    `json:"projectId"`
}

usage.go

newPayload := &Payload{
	ID:    issue.ID,
	Title: issue.Key,
	Type:  "object",
	Fields: Fields{
		[]FixVersion{
			FixVersion{
				Self:      v.Self,
				ID:        v.ID,
				Name:      v.Name,
				Archived:  v.Archived,
				Released:  v.Released,
				ProjectID: v.ProjectID,
			},
		},
	},
}