# File lib/arel/select_manager.rb, line 105
    def join relation, klass = Nodes::InnerJoin
      return self unless relation

      case relation
      when String, Nodes::SqlLiteral
        raise if relation.blank?
        klass = Nodes::StringJoin
      end

      @ctx.source.right << create_join(relation, nil, klass)
      self
    end