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: user_filter.rb
    path of file: ./repos/openproject/modules/costs/app/models/queries/time_entries/filters
    
    the code of the file until where you have to start completion: #-- copyright
# OpenP
    
  def allowed_values
    # We don't care for the first value as we do not display the values visibly
    @allowed_values ||= me_allowed_value + ::Principal
                       .in_visible_project
                       .pluck(:id)
                       .map { |id| [id, id.to_s] }
  end

  def where
    operator_strategy.sql_for_field(values_replaced, self.class.model.table_name, self.class.key)
  end

  def type
    :list_optional
  end

  def self.key
    :user_id
  end
end