Fix Elasticsearch::Transport::Transport::Errors::BadRequest

CHANGELOG-EE.md

 Please view this file on the master branch, on stable branches it's out of date.
+## 8.13.1
+
+  - Fix Elasticsearch::Transport::Transport::Errors::BadRequest when ES is enabled. #21036
+
 ## 8.13.0 (2016-10-22)
   - Cache the last usage data to avoid unicorn timeouts

app/models/diff_note.rb

 class DiffNote < Note
+  # Elastic search configuration (it does not support STI properly)
+  document_type 'note'
+  index_name [Rails.application.class.parent_name.downcase, Rails.env].join('-')
+  include Elastic::NotesSearch
+
   include NoteOnDiff
   serialize :original_position, Gitlab::Diff::Position

app/models/legacy_diff_note.rb

 class LegacyDiffNote < Note
+  # Elastic search configuration (it does not support STI properly)
+  document_type 'note'
+  index_name [Rails.application.class.parent_name.downcase, Rails.env].join('-')
+  include Elastic::NotesSearch
+
   include NoteOnDiff
   serialize :st_diff

spec/models/concerns/elastic/note_spec.rb

@@ -29,6 +29,24 @@ describe Note, elastic: true do
     expect(described_class.elastic_search('term', options: options).total_count).to eq(1)
   end
+  it "indexes && searches diff notes" do
+    notes = []
+
+    Sidekiq::Testing.inline! do
+      notes << create(:diff_note_on_merge_request, note: "term")
+      notes << create(:diff_note_on_commit, note: "term")
+      notes << create(:legacy_diff_note_on_merge_request, note: "term")
+      notes << create(:legacy_diff_note_on_commit, note: "term")
+
+      Gitlab::Elastic::Helper.refresh_index
+    end
+
+    project_ids = notes.map { |note| note.noteable.project.id }
+    options = { project_ids: project_ids }
+
+    expect(described_class.elastic_search('term', options: options).total_count).to eq(4)
+  end
+
   it "returns json with all needed elements" do
     note = create :note