Rename issuables_assigned_message method

app/services/issuable_links/create_service.rb

@@ -17,7 +17,7 @@ module IssuableLinks
       # otherwise create issue links for the issues which
       # are still not assigned and return success message.
       if render_conflict_error?
-        return error(issuables_assigned_message, 409)
+        return error(issuables_already_assigned_message, 409)
       end
 
       if render_not_found_error?
@@ -110,7 +110,7 @@ module IssuableLinks
       {}
     end
 
-    def issuables_assigned_message
+    def issuables_already_assigned_message
       _('%{issuable}(s) already assigned' % { issuable: target_issuable_type.capitalize })
     end
 

ee/app/services/epic_links/create_service.rb

@@ -87,12 +87,8 @@ module EpicLinks
       @descendants ||= issuable.group.self_and_descendants
     end
 
-    def issuables_assigned_message
-      'Epic(s) already assigned'
-    end
-
-    def issuables_not_found_message
-      'No Epic found for given params'
+    def target_issuable_type
+      :epic
     end
   end
 end

ee/spec/services/epic_links/create_service_spec.rb

@@ -10,7 +10,7 @@ RSpec.describe EpicLinks::CreateService do
     let(:user) { create(:user) }
     let(:epic) { create(:epic, group: group) }
     let(:epic_to_add) { create(:epic, group: group) }
-    let(:expected_error) { 'No Epic found for given params' }
+    let(:expected_error) { 'No matching epic found. Make sure that you are adding a valid epic URL.' }
     let(:expected_code) { 404 }
 
     let(:valid_reference) { epic_to_add.to_reference(full: true) }