Expose mergeRequestCounts for Issue GraphQL type

Changelog: changed

app/graphql/types/issue_type.rb

@@ -60,6 +60,8 @@ module Types
           description: 'Number of upvotes the issue has received.'
     field :downvotes, GraphQL::Types::Int, null: false,
           description: 'Number of downvotes the issue has received.'
+    field :merge_requests_count, GraphQL::INT_TYPE, null: false,
+          description: 'Number of merge requests that close the issue on merge.'
     field :user_notes_count, GraphQL::Types::Int, null: false,
           description: 'Number of user notes of the issue.',
           resolver: Resolvers::UserNotesCountResolver

doc/api/graphql/reference/index.md

@@ -9080,6 +9080,7 @@ Relationship between an epic and an issue.
 | <a id="epicissueiid"></a>`iid` | [`ID!`](#id) | Internal ID of the issue. |
 | <a id="epicissueiteration"></a>`iteration` | [`Iteration`](#iteration) | Iteration of the issue. |
 | <a id="epicissuelabels"></a>`labels` | [`LabelConnection`](#labelconnection) | Labels of the issue. (see [Connections](#connections)) |
+| <a id="epicissuemergerequestscount"></a>`mergeRequestsCount` | [`Int!`](#int) | Number of merge requests that close the issue on merge. |
 | <a id="epicissuemetricimages"></a>`metricImages` | [`[MetricImage!]`](#metricimage) | Metric images associated to the issue. |
 | <a id="epicissuemilestone"></a>`milestone` | [`Milestone`](#milestone) | Milestone of the issue. |
 | <a id="epicissuemoved"></a>`moved` | [`Boolean`](#boolean) | Indicates if issue got moved from other project. |
@@ -10153,6 +10154,7 @@ Returns [`VulnerabilitySeveritiesCount`](#vulnerabilityseveritiescount).
 | <a id="issueiid"></a>`iid` | [`ID!`](#id) | Internal ID of the issue. |
 | <a id="issueiteration"></a>`iteration` | [`Iteration`](#iteration) | Iteration of the issue. |
 | <a id="issuelabels"></a>`labels` | [`LabelConnection`](#labelconnection) | Labels of the issue. (see [Connections](#connections)) |
+| <a id="issuemergerequestscount"></a>`mergeRequestsCount` | [`Int!`](#int) | Number of merge requests that close the issue on merge. |
 | <a id="issuemetricimages"></a>`metricImages` | [`[MetricImage!]`](#metricimage) | Metric images associated to the issue. |
 | <a id="issuemilestone"></a>`milestone` | [`Milestone`](#milestone) | Milestone of the issue. |
 | <a id="issuemoved"></a>`moved` | [`Boolean`](#boolean) | Indicates if issue got moved from other project. |

spec/graphql/types/issue_type_spec.rb

@@ -15,7 +15,7 @@ RSpec.describe GitlabSchema.types['Issue'] do
 
   it 'has specific fields' do
     fields = %i[id iid title description state reference author assignees updated_by participants labels milestone due_date
-                confidential discussion_locked upvotes downvotes user_notes_count user_discussions_count web_path web_url relative_position
+                confidential discussion_locked upvotes downvotes merge_requests_count user_notes_count user_discussions_count web_path web_url relative_position
                 emails_disabled subscribed time_estimate total_time_spent human_time_estimate human_total_time_spent closed_at created_at updated_at task_completion_status
                 design_collection alert_management_alert severity current_user_todos moved moved_to
                 create_note_email timelogs project_id]