validate_reflection!

# File activerecord/lib/active_record/reflection.rb, line 438
        def validate_reflection!
          return unless options[:foreign_key].is_a?(Array)

          message = <<~MSG.squish
            Passing #{options[:foreign_key]} array to :foreign_key option
            on the #{active_record}##{name} association is not supported.
            Use the query_constraints: #{options[:foreign_key]} option instead to represent a composite foreign key.
          MSG
          raise ArgumentError, message
        end