Adds expanded triggered pipeline in the API

app/controllers/projects/pipelines_controller.rb

@@ -69,7 +69,7 @@ class Projects::PipelinesController < Projects::ApplicationController
 
         render json: PipelineSerializer
           .new(project: @project, current_user: @current_user)
-          .represent(@pipeline, grouped: true)
+          .represent(@pipeline, grouped: true, expanded: params[:expanded].to_a)
       end
     end
   end

ee/app/serializers/triggered_pipeline_entity.rb

@@ -15,8 +15,12 @@ class TriggeredPipelineEntity < Grape::Entity
 
   expose :details do
     expose :detailed_status, as: :status, with: DetailedStatusEntity
+    expose :ordered_stages, as: :stages, using: StageEntity, if: -> (_, opts) { expand?(opts) }
   end
 
+  expose :triggered_by_pipeline, as: :triggered_by, with: TriggeredPipelineEntity, if: -> (_, opts) { expand_for_path?(opts, :triggered_by) }
+  expose :triggered_pipelines, as: :triggered, using: TriggeredPipelineEntity, if: -> (_, opts) { expand_for_path?(opts, :triggered) }
+
   expose :project, using: ProjectEntity
 
   private
@@ -26,4 +30,12 @@ class TriggeredPipelineEntity < Grape::Entity
   def detailed_status
     pipeline.detailed_status(request.current_user)
   end
+
+  def expand?(opts)
+    opts[:expanded].to_a.include?(pipeline.id)
+  end
+
+  def expand_for_path?(opts, path)
+    opts[:attr_path].last == path && expand?(opts)
+  end
 end