XWiki.ClassSheet generates sheets which double escape the special characters in the document titles upon usage of the sheet

To reproduce:

• create a class using XWiki.XWikiClasses
  • it will be created using XWiki.ClassSheet as sheet
• Create the sheet for this class, using the button displayed by XWiki.ClassSheet, bind it to the class
• Create a document with an instance of an object in it, with an ampersand in the title or two adjacent whitespaces

Expected result:

• The ampersand is rendered as an ampersand, the two adjacent whitespaces are rendered as such
  Actual result:
• The ampersand is rendered as & while the whitespace is rendered as  

This is because, in the title generated for the sheet by XWiki.ClassSheet, the title of the document that uses the sheet is displayed using services.display.title(...) which, probably quite legitimate, already renders the special characters as entities.