Can not use mod operators (%) in when clause.

When I study drools , I write a rule use divide operator

rule "Buzz" salience 2
 when
  $n: Number( this / 5 == 3 )
 then
  System.out.println("Buzz");
end

It's OK.

But:

rule "Buzz" salience 2
 when
  $n: Number( this % 5 == 0 )
 then
  System.out.println("Buzz");
end

Report parser error: Unable to Analyse Expression this % 5 == 0:

The drools document mentioned the same example:

Person( age > 100 && ( age % 10 == 0 ) )
% is Multiplicative operators, why parser error?