Add confidentiality filtering to epics api endpoints

- add the filter to the REST API endpoint
- add the filter to the graphql epics endpoint

changelogs/unreleased/218624-roadmaps-conf-filter.yml

+---
+title: Add confidentiality filtering to the epics REST API and GraphQL endpoints
+merge_request: 51105
+author:
+type: added

doc/api/graphql/reference/gitlab_schema.graphql

@@ -1449,6 +1449,11 @@ type BoardEpic implements CurrentUserTodos & Noteable {
     """
     before: String
 
+    """
+    Filter epics by given confidentiality
+    """
+    confidential: Boolean
+
     """
     List items overlapping a time frame defined by startDate..endDate (if one
     date is provided, both must be present) Deprecated in 13.5: Use timeframe.end.
@@ -8003,6 +8008,11 @@ type Epic implements CurrentUserTodos & Noteable {
     """
     before: String
 
+    """
+    Filter epics by given confidentiality
+    """
+    confidential: Boolean
+
     """
     List items overlapping a time frame defined by startDate..endDate (if one
     date is provided, both must be present) Deprecated in 13.5: Use timeframe.end.
@@ -9892,6 +9902,11 @@ type Group {
     """
     authorUsername: String
 
+    """
+    Filter epics by given confidentiality
+    """
+    confidential: Boolean
+
     """
     List items overlapping a time frame defined by startDate..endDate (if one
     date is provided, both must be present) Deprecated in 13.5: Use timeframe.end.
@@ -10010,6 +10025,11 @@ type Group {
     """
     before: String
 
+    """
+    Filter epics by given confidentiality
+    """
+    confidential: Boolean
+
     """
     List items overlapping a time frame defined by startDate..endDate (if one
     date is provided, both must be present) Deprecated in 13.5: Use timeframe.end.

doc/api/graphql/reference/gitlab_schema.json

@@ -3944,6 +3944,16 @@
                   },
                   "defaultValue": "true"
                 },
+                {
+                  "name": "confidential",
+                  "description": "Filter epics by given confidentiality",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "Boolean",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
                 {
                   "name": "after",
                   "description": "Returns the elements in the list that come after the specified cursor.",
@@ -22361,6 +22371,16 @@
                   },
                   "defaultValue": "true"
                 },
+                {
+                  "name": "confidential",
+                  "description": "Filter epics by given confidentiality",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "Boolean",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
                 {
                   "name": "after",
                   "description": "Returns the elements in the list that come after the specified cursor.",
@@ -27505,6 +27525,16 @@
                     "ofType": null
                   },
                   "defaultValue": "true"
+                },
+                {
+                  "name": "confidential",
+                  "description": "Filter epics by given confidentiality",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "Boolean",
+                    "ofType": null
+                  },
+                  "defaultValue": null
                 }
               ],
               "type": {
@@ -27745,6 +27775,16 @@
                   },
                   "defaultValue": "true"
                 },
+                {
+                  "name": "confidential",
+                  "description": "Filter epics by given confidentiality",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "Boolean",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
                 {
                   "name": "after",
                   "description": "Returns the elements in the list that come after the specified cursor.",

ee/app/graphql/resolvers/epics_resolver.rb

@@ -46,6 +46,10 @@ module Resolvers
              description: 'Include epics from descendant groups',
              default_value: true
 
+    argument :confidential, GraphQL::BOOLEAN_TYPE,
+             required: false,
+             description: 'Filter epics by given confidentiality'
+
     type Types::EpicType, null: true
 
     def ready?(**args)

ee/lib/api/epics.rb

@@ -39,6 +39,7 @@ module API
         optional :include_ancestor_groups, type: Boolean, default: false, desc: 'Include epics from ancestor groups'
         optional :include_descendant_groups, type: Boolean, default: true, desc: 'Include epics from descendant groups'
         optional :my_reaction_emoji, type: String, desc: 'Return epics reacted by the authenticated user by the given emoji'
+        optional :confidential, type: Boolean, desc: 'Return epics with given confidentiality'
         use :pagination
       end
       [':id/epics', ':id/-/epics'].each do |path|

ee/spec/requests/api/epics_spec.rb

@@ -221,6 +221,16 @@ RSpec.describe API::Epics do
         expect_paginated_array_response([epic2.id, epic.id])
       end
 
+      it 'returns epics matching given confidentiality' do
+        group.add_developer(user)
+
+        epic3 = create(:epic, group: group, confidential: true)
+
+        get api(url, user), params: { confidential: true }
+
+        expect_paginated_array_response([epic3.id])
+      end
+
       it 'has upvote/downvote information' do
         create(:award_emoji, name: 'thumbsup', awardable: epic, user: user )
         create(:award_emoji, name: 'thumbsdown', awardable: epic2, user: user )