You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: 20230810074642_add_optional_entity_to_members.rb
    path of file: ./repos/openproject/db/migrate
    
    the code of the file until where you have to start completion: class AddOptionalEntityToMembers < ActiveRecord::Migration[7.0]
  def change
    add_reference :members, :entity, foreign_key: false, polymorphic: true, index: true
    remove_index :members, %i[user_id project_id], unique: true

    add_index :members, %i[user_id project_id],
              unique: true,
  
    
  def change
    add_reference :members, :entity, foreign_key: false, polymorphic: true, index: true
    remove_index :members, %i[user_id project_id], unique: true

    add_index :members, %i[user_id project_id],
              unique: true,
              where: "entity_type IS NULL AND entity_id IS NULL",
              name: 'index_members_on_user_id_and_project_without_entity'

    add_index :members, %i[user_id project_id entity_type entity_id],
              unique: true,
              where: "entity_type IS NOT NULL AND entity_id IS NOT NULL",
              name: 'index_members_on_user_id_and_project_with_entity'
  end