# File lib/aws/s3/client.rb, line 1051
        def xml_validation_message(obj)
          if obj.respond_to?(:to_str)
            obj = obj.to_str
          elsif obj.respond_to?(:to_xml)
            obj = obj.to_xml
          end

          error = nil
          begin
            REXML::Document.new(obj)
          rescue => e
            error = e
          end
          "contains invalid XML: #{error}" if error
        end