Given the rule
=============================================
rule x
dialect "mvel"
when
then
List<Integer> l = new ArrayList<Integer>();
end
=============================================
we get the error
=============================================
Unable to Analyse Expression List x = new ArrayList<Integer>();
[Error: Failed to compileShared: 1 compilation error(s):

• (1,23) could not resolve class: ArrayList<Integer>]
  [Near : {... List x = new ArrayList<Integer>(); ....}

  ]
  ^
  [Line: 1, Column: 23]