Fix creating confidential issues of public epics

Fixes a regression. It was not possible to create
confidential issues as child of public epics.

ee/app/services/ee/issues/create_service.rb

@@ -18,7 +18,7 @@ module EE
         epic = params.delete(:epic)
 
         if epic
-          issue.confidential = epic.confidential?
+          issue.confidential = true if epic.confidential?
 
           EpicIssues::CreateService.new(epic, current_user, { target_issuable: issue }).execute
         else

ee/spec/services/ee/issues/create_service_spec.rb

@@ -84,10 +84,9 @@ RSpec.describe Issues::CreateService do
             end
           end
 
-          context 'when adding an issue to confidential epic' do
-            let(:confidential_epic) { create(:epic, group: group, confidential: true) }
-
-            it 'creates a confidential issue' do
+          context 'when adding a public issue to confidential epic' do
+            it 'creates confidential child issue' do
+              confidential_epic = create(:epic, group: group, confidential: true)
               params = { title: 'confidential issue', epic_id: confidential_epic.id }
 
               issue = described_class.new(project, user, params).execute
@@ -95,6 +94,16 @@ RSpec.describe Issues::CreateService do
               expect(issue.confidential).to eq(true)
             end
           end
+
+          context 'when adding a confidential issue to public epic' do
+            it 'creates a confidential child issue' do
+              params = { title: 'confidential issue', epic_id: epic.id, confidential: true }
+
+              issue = described_class.new(project, user, params).execute
+
+              expect(issue.confidential).to eq(true)
+            end
+          end
         end
       end
     end