Fix #5953 - Add GET /api/v1/accounts/:id/lists (#5983)

app/controllers/api/v1/accounts/lists_controller.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+class Api::V1::Accounts::ListsController < Api::BaseController
+  before_action -> { doorkeeper_authorize! :read }
+  before_action :require_user!
+  before_action :set_account
+
+  respond_to :json
+
+  def index
+    @lists = @account.lists.where(account: current_account)
+    render json: @lists, each_serializer: REST::ListSerializer
+  end
+
+  private
+
+  def set_account
+    @account = Account.find(params[:account_id])
+  end
+end