Transform an XMLObject with XMLElements with empty attributes

Question

I would like to transform a an XMLObject so as to replace all the non empty attributes of the XMLElements by empty attributes.

The aim is to have a smaller structure that I could visualize with ExpressionTreePlot.

May you help me to define a appropriated code with this sample to start ?

xml = XMLObject[
  "Document"][{XMLObject["Doctype"]["DEXXMLDoc", 
   "System" -> "DEXXMLDoc.DTD"]}, 
 XMLElement[
  "DEXXMLDoc", {"name" -> "RSM-a.xml", "creator" -> "DX8", 
   "version" -> "8.0.6"}, {XMLElement[
    "designInfo", {"studyType" -> "ResponseSurface", 
     "designType" -> "CCD", "noOfRuns" -> "20", "noOfFactors" -> "3", 
     "noOfResponses" -> "2"}, {XMLElement[
      "designNotes", {}, {"This data file created by Design-Expert \
6"}]}], XMLElement[
    "blockInfo", {}, {XMLElement[
      "block", {"code" -> "0", "name" -> "Block 1"}, {}], 
     XMLElement["block", {"code" -> "1", "name" -> "Block 2"}, {}]}]
   }
  ]
 ]

Thank you for your help

Answer 1

Block[{XMLElement},
    XMLElement[x_, y : Except[{}], z_] := XMLElement[x, {}, z];
    xml
] 

XMLObject[
  "Document"][{XMLObject["Doctype"]["DEXXMLDoc", 
   "System" -> "DEXXMLDoc.DTD"]}, 
 XMLElement[
  "DEXXMLDoc", {}, {XMLElement[
    "designInfo", {}, {XMLElement[
      "designNotes", {}, {"This data file created by Design-Expert \
6"}]}], XMLElement[
    "blockInfo", {}, {XMLElement["block", {}, {}], 
     XMLElement["block", {}, {}]}]}]]