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
}
ListMergeRequests gets all merge requests. The state
parameter can be used to get only merge requests with a given state (opened,
closed, or merged) or all of them (all). The pagination parameters page and
per_page can be used to restrict the list of merge requests.

GitLab API docs:
https://docs.gitlab.com/ce/api/merge_requests.html#list-merge-requests
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"`
}