func (s *MergeRequestsService) GetTimeSpent(pid interface{}, mergeRequest int, options ...OptionFunc) (*TimeStats, *Response, error) {
	return s.timeStats.getTimeSpent(pid, "merge_requests", mergeRequest, options...)
}
GetTimeSpent gets the spent time for a single project merge request.

GitLab API docs:
https://docs.gitlab.com/ce/api/merge_requests.html#get-time-tracking-stats
package gitlab
import (
	"fmt"
	"net/url"
	"time"
)
type MergeRequestsService struct {
	client    *Client
	timeStats *timeStatsService
}
type MergeRequest struct {
	ID             int    `json:"id"`
	IID            int    `json:"iid"`
	ProjectID      int    `json:"project_id"`
	Title          string `json:"title"`
	Description    string `json:"description"`
	WorkInProgress bool   `json:"work_in_progress"`
	State          string `json:"state"`
	CreatedAt      string `json:"created_at"`
	UpdatedAt      string `json:"updated_at"`
	TargetBranch   string `json:"target_branch"`
	SourceBranch   string `json:"source_branch"`
	Upvotes        int    `json:"upvotes"`
	Downvotes      int    `json:"downvotes"`
	Author         struct {
		Name      string `json:"name"`
		Username  string `json:"username"`
		ID        int    `json:"id"`
		State     string `json:"state"`
		AvatarURL string `json:"avatar_url"`
	} `json:"author"`
	Assignee struct {
		Name      string `json:"name"`
		Username  string `json:"username"`
		ID        int    `json:"id"`
		State     string `json:"state"`
		AvatarURL string `json:"avatar_url"`
	} `json:"assignee"`
	SourceProjectID int      `json:"source_project_id"`
	TargetProjectID int      `json:"target_project_id"`
	Labels          []string `json:"labels"`
	Milestone       struct {
		ID          int        `json:"id"`
		Iid         int        `json:"iid"`
		ProjectID   int        `json:"project_id"`
		Title       string     `json:"title"`
		Description string     `json:"description"`
		State       string     `json:"state"`
		CreatedAt   *time.Time `json:"created_at"`
		UpdatedAt   *time.Time `json:"updated_at"`
		DueDate     string     `json:"due_date"`
	} `json:"milestone"`
	MergeWhenPipelineSucceeds bool   `json:"merge_when_pipeline_succeeds"`
	MergeStatus               string `json:"merge_status"`
	SHA                       string `json:"sha"`
	Subscribed                bool   `json:"subscribed"`
	UserNotesCount            int    `json:"user_notes_count"`
	SouldRemoveSourceBranch   bool   `json:"should_remove_source_branch"`
	ForceRemoveSourceBranch   bool   `json:"force_remove_source_branch"`
	Changes                   []struct {
		OldPath     string `json:"old_path"`
		NewPath     string `json:"new_path"`
		AMode       string `json:"a_mode"`
		BMode       string `json:"b_mode"`
		Diff        string `json:"diff"`
		NewFile     bool   `json:"new_file"`
		RenamedFile bool   `json:"renamed_file"`
		DeletedFile bool   `json:"deleted_file"`
	} `json:"changes"`
	WebURL string `json:"web_url"`
}
func (m MergeRequest) String() string {
	return Stringify(m)
}
type MergeRequestApprovals struct {
	ID                int        `json:"id"`
	ProjectID         int        `json:"project_id"`
	Title             string     `json:"title"`
	Description       string     `json:"description"`
	State             string     `json:"state"`
	CreatedAt         *time.Time `json:"created_at"`
	UpdatedAt         *time.Time `json:"updated_at"`
	MergeStatus       string     `json:"merge_status"`
	ApprovalsRequired int        `json:"approvals_required"`
	ApprovalsMissing  int        `json:"approvals_missing"`
	ApprovedBy        []struct {
		User struct {
			Name      string `json:"name"`
			Username  string `json:"username"`
			ID        int    `json:"id"`
			State     string `json:"state"`
			AvatarURL string `json:"avatar_url"`
			WebURL    string `json:"web_url"`
		} `json:"user"`
	} `json:"approved_by"`
}
func (m MergeRequestApprovals) String() string {
	return Stringify(m)
}
type ListMergeRequestsOptions struct {
	ListOptions
	State           *string    `url:"state,omitempty" json:"state,omitempty"`
	OrderBy         *string    `url:"order_by,omitempty" json:"order_by,omitempty"`
	Sort            *string    `url:"sort,omitempty" json:"sort,omitempty"`
	Milestone       *string    `url:"milestone,omitempty" json:"milestone,omitempty"`
	View            *string    `url:"view,omitempty" json:"view,omitempty"`
	Labels          Labels     `url:"labels,omitempty" json:"labels,omitempty"`
	CreatedAfter    *time.Time `url:"created_after,omitempty" json:"created_after,omitempty"`
	CreatedBefore   *time.Time `url:"created_before,omitempty" json:"created_before,omitempty"`
	Scope           *string    `url:"scope,omitempty" json:"scope,omitempty"`
	AuthorID        *int       `url:"author_id,omitempty" json:"author_id,omitempty"`
	AssigneeID      *int       `url:"assignee_id,omitempty" json:"assignee_id,omitempty"`
	MyReactionEmoji *string    `url:"my_reaction_emoji,omitempty" json:"my_reaction_emoji,omitempty"`
}
func (s *MergeRequestsService) ListMergeRequests(opt *ListMergeRequestsOptions, options ...OptionFunc) ([]*MergeRequest, *Response, error) {
	req, err := s.client.NewRequest("GET", "merge_requests", opt, options)
	if err != nil {
		return nil, nil, err
	}
	var m []*MergeRequest
	resp, err := s.client.Do(req, &m)
	if err != nil {
		return nil, resp, err
	}
	return m, resp, err
}
type ListProjectMergeRequestsOptions struct {
	ListOptions
	IIDs            []int      `url:"iids[],omitempty" json:"iids,omitempty"`
	State           *string    `url:"state,omitempty" json:"state,omitempty"`
	OrderBy         *string    `url:"order_by,omitempty" json:"order_by,omitempty"`
	Sort            *string    `url:"sort,omitempty" json:"sort,omitempty"`
	Milestone       *string    `url:"milestone,omitempty" json:"milestone,omitempty"`
	View            *string    `url:"view,omitempty" json:"view,omitempty"`
	Labels          Labels     `url:"labels,omitempty" json:"labels,omitempty"`
	CreatedAfter    *time.Time `url:"created_after,omitempty" json:"created_after,omitempty"`
	CreatedBefore   *time.Time `url:"created_before,omitempty" json:"created_before,omitempty"`
	Scope           *string    `url:"scope,omitempty" json:"scope,omitempty"`
	AuthorID        *int       `url:"author_id,omitempty" json:"author_id,omitempty"`
	AssigneeID      *int       `url:"assignee_id,omitempty" json:"assignee_id,omitempty"`
	MyReactionEmoji *string    `url:"my_reaction_emoji,omitempty" json:"my_reaction_emoji,omitempty"`
}
func (s *MergeRequestsService) ListProjectMergeRequests(pid interface{}, opt *ListProjectMergeRequestsOptions, options ...OptionFunc) ([]*MergeRequest, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/merge_requests", url.QueryEscape(project))
	req, err := s.client.NewRequest("GET", u, opt, options)
	if err != nil {
		return nil, nil, err
	}
	var m []*MergeRequest
	resp, err := s.client.Do(req, &m)
	if err != nil {
		return nil, resp, err
	}
	return m, resp, err
}
func (s *MergeRequestsService) GetMergeRequest(pid interface{}, mergeRequest int, options ...OptionFunc) (*MergeRequest, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/merge_requests/%d", url.QueryEscape(project), mergeRequest)
	req, err := s.client.NewRequest("GET", u, nil, options)
	if err != nil {
		return nil, nil, err
	}
	m := new(MergeRequest)
	resp, err := s.client.Do(req, m)
	if err != nil {
		return nil, resp, err
	}
	return m, resp, err
}
func (s *MergeRequestsService) GetMergeRequestApprovals(pid interface{}, mergeRequest int, options ...OptionFunc) (*MergeRequestApprovals, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/merge_requests/%d/approvals", url.QueryEscape(project), mergeRequest)
	req, err := s.client.NewRequest("GET", u, nil, options)
	if err != nil {
		return nil, nil, err
	}
	a := new(MergeRequestApprovals)
	resp, err := s.client.Do(req, a)
	if err != nil {
		return nil, resp, err
	}
	return a, resp, err
}
func (s *MergeRequestsService) GetMergeRequestCommits(pid interface{}, mergeRequest int, options ...OptionFunc) ([]*Commit, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/merge_requests/%d/commits", url.QueryEscape(project), mergeRequest)
	req, err := s.client.NewRequest("GET", u, nil, options)
	if err != nil {
		return nil, nil, err
	}
	var c []*Commit
	resp, err := s.client.Do(req, &c)
	if err != nil {
		return nil, resp, err
	}
	return c, resp, err
}
func (s *MergeRequestsService) GetMergeRequestChanges(pid interface{}, mergeRequest int, options ...OptionFunc) (*MergeRequest, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/merge_requests/%d/changes", url.QueryEscape(project), mergeRequest)
	req, err := s.client.NewRequest("GET", u, nil, options)
	if err != nil {
		return nil, nil, err
	}
	m := new(MergeRequest)
	resp, err := s.client.Do(req, m)
	if err != nil {
		return nil, resp, err
	}
	return m, resp, err
}
type CreateMergeRequestOptions struct {
	Title           *string `url:"title,omitempty" json:"title,omitempty"`
	Description     *string `url:"description,omitempty" json:"description,omitempty"`
	SourceBranch    *string `url:"source_branch,omitempty" json:"source_branch,omitempty"`
	TargetBranch    *string `url:"target_branch,omitempty" json:"target_branch,omitempty"`
	AssigneeID      *int    `url:"assignee_id,omitempty" json:"assignee_id,omitempty"`
	TargetProjectID *int    `url:"target_project_id,omitempty" json:"target_project_id,omitempty"`
}
func (s *MergeRequestsService) CreateMergeRequest(pid interface{}, opt *CreateMergeRequestOptions, options ...OptionFunc) (*MergeRequest, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/merge_requests", url.QueryEscape(project))
	req, err := s.client.NewRequest("POST", u, opt, options)
	if err != nil {
		return nil, nil, err
	}
	m := new(MergeRequest)
	resp, err := s.client.Do(req, m)
	if err != nil {
		return nil, resp, err
	}
	return m, resp, err
}
type UpdateMergeRequestOptions struct {
	Title        *string `url:"title,omitempty" json:"title,omitempty"`
	Description  *string `url:"description,omitempty" json:"description,omitempty"`
	TargetBranch *string `url:"target_branch,omitempty" json:"target_branch,omitempty"`
	AssigneeID   *int    `url:"assignee_id,omitempty" json:"assignee_id,omitempty"`
	Labels       Labels  `url:"labels,comma,omitempty" json:"labels,omitempty"`
	MilestoneID  *int    `url:"milestone_id,omitempty" json:"milestone_id,omitempty"`
	StateEvent   *string `url:"state_event,omitempty" json:"state_event,omitempty"`
}
func (s *MergeRequestsService) UpdateMergeRequest(pid interface{}, mergeRequest int, opt *UpdateMergeRequestOptions, options ...OptionFunc) (*MergeRequest, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/merge_requests/%d", url.QueryEscape(project), mergeRequest)
	req, err := s.client.NewRequest("PUT", u, opt, options)
	if err != nil {
		return nil, nil, err
	}
	m := new(MergeRequest)
	resp, err := s.client.Do(req, m)
	if err != nil {
		return nil, resp, err
	}
	return m, resp, err
}
type AcceptMergeRequestOptions struct {
	MergeCommitMessage        *string `url:"merge_commit_message,omitempty" json:"merge_commit_message,omitempty"`
	ShouldRemoveSourceBranch  *bool   `url:"should_remove_source_branch,omitempty" json:"should_remove_source_branch,omitempty"`
	MergeWhenPipelineSucceeds *bool   `url:"merge_when_pipeline_succeeds,omitempty" json:"merge_when_pipeline_succeeds,omitempty"`
	Sha                       *string `url:"sha,omitempty" json:"sha,omitempty"`
}
func (s *MergeRequestsService) AcceptMergeRequest(pid interface{}, mergeRequest int, opt *AcceptMergeRequestOptions, options ...OptionFunc) (*MergeRequest, *Response, error) {
	project, err := parseID(pid)
	if err != nil {
		return nil, nil, err
	}
	u := fmt.Sprintf("projects/%s/merge_requests/%d/merge", url.QueryEscape(project), mergeRequest)
	req, err := s.client.NewRequest("PUT", u, opt, options)
	if err != nil {
		return nil, nil, err
	}
	m := new(MergeRequest)
	resp, err := s.client.Do(req, m)
	if err != nil {
		return nil, resp, err
	}
	return m, resp, err
}
func (s *MergeRequestsService) SetTimeEstimate(pid interface{}, mergeRequest int, opt *SetTimeEstimateOptions, options ...OptionFunc) (*TimeStats, *Response, error) {
	return s.timeStats.setTimeEstimate(pid, "merge_requests", mergeRequest, opt, options...)
}
func (s *MergeRequestsService) ResetTimeEstimate(pid interface{}, mergeRequest int, options ...OptionFunc) (*TimeStats, *Response, error) {
	return s.timeStats.resetTimeEstimate(pid, "merge_requests", mergeRequest, options...)
}
func (s *MergeRequestsService) AddSpentTime(pid interface{}, mergeRequest int, opt *AddSpentTimeOptions, options ...OptionFunc) (*TimeStats, *Response, error) {
	return s.timeStats.addSpentTime(pid, "merge_requests", mergeRequest, opt, options...)
}
func (s *MergeRequestsService) ResetSpentTime(pid interface{}, mergeRequest int, options ...OptionFunc) (*TimeStats, *Response, error) {
	return s.timeStats.resetSpentTime(pid, "merge_requests", mergeRequest, options...)
}