$doc.display() does not find new properties until Save Objects is executed

As posted on the XWiki-users mailing list:

After adding a new property "myNewProp" to class "myClass", executing
$doc.display("myNewProp")
in documents already containing instances of "myClass" returns nothing until I do "Edit Objects/Save Objects" on those documents.

Ludovic's reply:

It's not the intended behavior. It seems to be a bug in the $doc.display() function
A workaround is to use a different display function

#set($obj = $doc.getObject("XWiki.MyClass",0))
$doc.display("myNewProp", "edit", $obj)

You should add a task to http://jira.xwiki.org to fix this issue