Add number sign on external issue reference text

app/models/external_issue.rb

@@ -34,7 +34,15 @@ class ExternalIssue
     %r{(?<issue>\b([A-Z][A-Z0-9_]+-)\d+)}
   end
+  def self.reference_prefix
+    '#'
+  end
+
   def to_reference(_from_project = nil)
     id
   end
+
+  def reference_link_text(from_project = nil)
+    "#{self.class.reference_prefix}#{id}"
+  end
 end

spec/models/external_issue_spec.rb

@@ -36,4 +36,10 @@ describe ExternalIssue, models: true do
       expect(issue.title).to eq "External Issue #{issue}"
     end
   end
+
+  describe '#reference_link_text' do
+    it 'returns a String reference to the object' do
+      expect(issue.reference_link_text).to eq '#EXT-1234'
+    end
+  end
 end